In my July Blog I came up with a list of the 10 Challenges, one or more of which, anyone getting started in EAA is likely to face at some point.  I explained covered the first 3 of these providing a troubleshooting guide for each one.  If you haven't read that Blog yet, I suggest you start there.  In any case here again are the Top 10 Challenges:

1. Cannot Get the Camera to Connect to the Imaging SW
2.  Cannot See Anything in the Image
​3.  Can See Stars, but Not DSOs
​4.  Live Stacking Not Working
5.  Poor Focus
6.  Elongated stars
7.  Comet Shaped Stars
8.  Noisy background
9.  Significant Vignetting
10. Plate Solve Fails
​
​In this Blog I will address the 4th and 5th of these challenges.

#4. Live Stacking Not Working

​Live stacking is the key ingredient to EAA.  The ability to take many short exposure sub frames and stack them in real time, averaging out the background noise so as to improve the SNR is why we can see so much detail in Deep Sky Objects (DSOs) as we allow the stacking process to proceed.  It is not uncommon for the Live Stacking software (SharpCap, ASILive, etc.) to reject some frames from the stacking process for a number of different reasons.  This is no reason for alarm and can be a good thing as it may be eliminating bad frames from messing up the stacked image.  Moments of poor seeing, a light wind gust, errant mount behavior, etc. can cause a frame here or there to be rejected.  However, sometimes one finds that after the first frame is captured, no subsequent frames are successfully stacked no matter how long we wait.  There are several reasons why this may happen.  In this Blog we will use Sharpcap as our example Live Stacking software.  Other such software will behave generally the same, but may not have all of the stacking settings available to the user in Sharpcap.  Generally they don't.  Live Stacking is one aspect of EAA that you will not be able to check out during the daytime.  However, if you run into trouble at night, follow the guidelines below to, hopefully, quickly pinpoint and solve your problem.

​
   4A.  Check the "Align Frames" Box in the Live Stacking Feature

To begin stacking you must start the Live Stacking function and under "Controls" click "Align Frames".  This is likely only a novice oversight, but it doesn't hurt to check.

   4C. Elongated Stars

Elongated or egg shaped stars may be one of the most common reasons for live stacking to not work on some or all frames.  Live stacking software is looking for stars to be point like and may not identify a star shaped like an elipse as a star. Stars become elongated when the exposure time is too long for the mount to keep the stars from moving within the frame.  If you are using an Equatorial Mount, either go back and re-do the polar alignment or shorten the exposure time.  You should also make sure that your mount is up to the task for the given exposure time.  This includes keeping within the mount's rated capacity, obtaining a good balance of the optical tube and shielding the mount from gusts of wind.  If you are using an Alt-Az mount, it is important to keep the exposure short enough to avoid star elongation due to field rotation.  A maximum of 30sec is the general rule of thumb for Alt-Az mounts, but the fact is that longer exposures are possible in some areas of the sky such as due east and due west.  For a more in depth discussion on this check my page on Field Rotation.

   4D. Poor Frame Quality

Besides elongated stars there are other reasons that a frame can be rejected by the stacking algorithm.  Poor focus, poor seeing, bad collimation can all cause the overall frame quality to be rejected by the stacking algorithm.  Check the Full Width Half Maximum (FWHM) tab to see if frames are being rejected (highlighted red) from the stacking process because of star size.  You should use the focus tools under Focus Assistant under the Tools Tab at the top of the screen to make sure that you have good focus first.  You can also use a Bahtinov mask to check and optimize the focus if you prefer.  You can check for poor seeing with the Seeing Monitor under the Tools Tab at the top of the screen but make sure that you have a good focus first or the Seeing Monitor can be fooled.  

   4E. Forgot to Remove the Bahtinov Mask

Sometimes we so distracted that we forget to remove the Bahtinov mask if we used one to focus.  The distorted stars will give the imaging software agita and the stacking process will have problems.

   4F. Camera Issues

It is possible that frames get dropped because of problems with the connection between the camera and the software.  These can be due to cable timing issues between the SW asking for an image frame and the camera sending it over.  Try connecting the camera directly to the computer if it is not already.  You can also try a different USB cable.

   4G.  Check the Forums

When all else fails you may want to check the appropriate software forum where you can find additional help, especially for uncommon problems.  Here is the link to the Sharpcap forum forums.sharpcap.co.uk/index.php and here is the link to the ASIStudio forum bbs.zwoastro.com/t/asistudio

If live stacking is working well, very, very few frames should be dropped.  In fact, I find that if live stacking is working, I rarely see dropped frames.  

#5.  Poor Focus

Poor focus at best will result in soft images with important detail obscured, and at worst produce undiscernible images.  It can also adversely impact live stacking and the plate solving process.   During the daytime checkout of your setup, checking focus should be foremost on your list.  Focus on a distant object like a building, tree, power pole, etc.  The further away the better but even once you have achieved focus in daylight you will still have to fine tune it at night on the stars.

At night, you should focus right after everything is connected and the optical axis is pointed at a clear region in the night sky.  Start you viewing session by focusing on a region of the sky just after dusk with lots of stars.  There are a number of different tools available for focusing depending upon the software used and whether a motorized focuser is available.   Also, if you change focal length you may be far from focus at the new focal length.  With my SCT I find that I have to move the mirror with the focus knob almost all the way to the other side of focus when I change from f/10 to f/7 on my Edge C11.

  5A.  Manual Focus

If you do not have a motorized focuser it will be necessary to focus manually.  While one might think that they can tell when the optics is focused by looking at the image of a star field by eye it is unlikely that they would achieve the best possible focus without some feedback mechanism.  One of the simplest of these is an inexpensive Bahtinov mask to focus on a single bright star.  Placed over the front of the optical tube, the cutouts in this plastic mask cause the light passing through to create a diffraction pattern with two lines forming an "X" and a third passing through the "X" vertically.  When the third vertical line bisects the "X" the optics is well focused.  If necessary, increase the exposure to help make the pattern easy to discern.  A Bahtinov mask is capable of achieving a very good focus on par with other automated methods.  Sharpcap has a focus assistance tool for the Bahtinov mask that analyzes the diffraction pattern and gives a score to help determine the best focus point.

An alternative to the Bahtinov mask is to focus directly on a single star or a field of stars.  Sharpcap measures the pixel width of the star or stars and displays a value for the Full Width Half Maximum (FWHM).  A well focused star will cover the minimum number of pixel widths, hence will have the smallest possible FWHM number.   Use the FWHM method for a single star or the Multi-Star FWHM method for a field of stars.  Adjust focus while watching the FWHM feedback number until you have minimized it.

​  5B.  Auto Focus

If you have a motorized focuser you can use the software to focus automatically.  For this to work, the software must be able to connect to the focuser which will require that you download the appropriate ASCOM driver for the focuser from the focuser manufacturer's web site.  In addition, you will also need to download the ASCOM platform which you can find on the ASCOM web site ascom-standards.org/Downloads/Index.htm.  You can use the same focusing aids (Bahtinov Mask, FWHM, Multi-Star FWHM) in the auto focus mode as in the manual focus mode.  The difference is that the software will control the focuser based upon the focus score it calculates.

  5C.  Re-Focus Occasionally 

As the temperature drops throughout the night the optical tube will contract changing the optimal focus position.  For this reason it is a good idea to check the focus from time to time.  It will also be necessary to refocus if you remove or change a filter as the optical path length can change due to differences in filter glass thickness and/or indices of refraction.

  5D.  Elongated Stars

Elongated stars due to poor tracking, for instance, will make it difficult to achieve a good focus.  In that case, the reason for the elongated stars needs to be resolve before trying to refine the focus.

A good focus is key to a sharp image showing the best detail.  And, a good focus is important for the other ingredients of a successful EAA session including automatic stacking and plate solving.

EAA has been a rewarding endeavor for me over the past 15 years.  I have been able to see hundreds of interesting celestial objects from distant galaxies, nebulae, star clusters and more.  I started with a 9.25" SCT, moved up to a 14" model and then back down to a more portable 11" one.  I have done EAA  with multiple refractors and even a 6" Newtonian.  Over the years I graduated from analog video cameras to CMOS digital cameras and from sensors with 6.5mm diameters to one with a 28.3mm diagonal.   I went from single shot long frame captures to short sub-frame live stacking as well.  Needless to say, all of these transitions have not been without their challenges which have caused many frustrating nights along the way.  So that I have not suffered these trials in vain I decided to pen a series of Blogs to help others avoid or, at least, minimize their frustration when they encounter these same challenges.  Based upon my experience and what I know from what others have encountered, I have come up with what I think are the Top 10 common challenges in EAA.  Here is my list of these:

1. Cannot Get the Camera to Connect to the Imaging SW
2.  Cannot See Anything in the Image
​3.  Can See Stars, but Not DSOs
​4.  Live Stacking Not Working
5.  Poor Focus
6.  Elongated stars
7.  Comet Shaped Stars
8.  Noisy background
9.  Significant Vignetting
10. Plate Solve Fails

I will cover each of these in detail through a series of Blogs offering possible root causes and solutions to each.  These may not prevent everyone from suffering from the same, but should help to minimize the possibility of encountering one of these and possibly reducing the frustration level when dealing with one that raises its ugly head.   In this Blog I will discuss the first three of these which are pretty common for beginners to suffer through when first getting started.  Before jumping into these specific issues I would encourage any beginner to test out as much of their equipment as they can during the day.  It is better to discover problems and troubleshoot in the daylight rather than try to track down bad cables, etc. in the dark and loose valuable viewing time.  Obviously some issues cannot be discovered until darkness, but many can.

​So, let's start with the first one on the list, which is likely the first problem one would encounter, failure to get the imaging software to see the camera.

 #1.  Cannot Get the Camera to Connect to the Imaging SW

You are all set to start you EAA session and go to connect your favorite live stacking SW to your camera and then, nothing.  You close the SW and re-start it but still no connection.  You re-boot your computer and try again.  Still nothing.  You unplug and re-plug the USB cable to the camera and no joy.  What is the problem?  Below is a trouble shooting list starting with the simplest things to try.  Most likely the problem is with one of these, but there are no guarantees that the problem still doesn't persist after trying all of the trouble shooting tips below.

   1A. Check the SW Compatibility & Camera Drivers

The first thing to check is to make sure that the SW you are using is designed to work with your particular model of camera.  Some SW like ASILive from ZWO, or Starlight Live will only work with cameras from ZWO and Starlight Xpress, respectively.  So cameras from QHY, Player One, etc. will not connect to their SW.  Other SW like Sharpcap and The Sky X Live Stack will work with a host of cameras. The tables below show which cameras Sharpcap and TSX work with natively.  Note that for TSX there is a dependence upon which operating system is used on the computer.  Native support means that the SW has access to the most controls that the camera manufacturer offers and is the best way to connect to a camera when available.  To successfully connect the camera the latest version of the camera driver must installed prior to connecting to the camera.  The driver will be found on the camera manufacturer's web site.  This is true for all Live Stacking software including Sharpcap, ASILive, Starlight Live SW, etc.  Make sure that you have the latest driver as older drivers may not work with updated versions of the stacking software.  After loading the driver restart your computer.

Cameras not on the above lists may still work with Sharpcap, TSX or other live stacking SW (but not ASILive or Starlight Xpress Live) but only through an ASCOM connection.  In that case, the camera's ASCOM driver must be loaded from the camera manufacturer's web site along with the ASCOM platform before attempting to connect to the camera.  The ASCOM platform can be downloaded from the ASCOM web site here ascom-standards.org/Downloads/Index.htm

​Another thing to try is to see if there is an updated version of the software.  If so, download and try it.  This is especially true if you just got the latest version of a new camera.

    1B.  You Must Have 12V DC Power Connected for a Cooled Camera

If you are using a cooled camera, you must connect 12V power to the 12V DC power input for the cooler.  This is the case regardless of whether or not you intend to turn on the cooler.  Both Sharpcap and ASILive will automatically detect your camera if 12V is applied.  You can turn off the cooling function within the software but if you turn off the input power to the camera the software will drop the camera.

    1C. Check the Cable

If you have loaded the necessary drivers and restarted your computer and SW but your camera still will not connect, the next thing to check is the connection between the camera and the computer.  If the camera is directly connected to the computer without a USB hub between the two and does not work, try another cable.  It is preferable to use the cable which came with the camera but if that does not work or you do not have one, make sure that the USB cable you are using is the proper USB type cable (USB3, USB2, etc).  The camera manufacturer should specify this, but note that most recent cameras that I know of now use USB3 cables.  Also, use the shortest USB cable that you can, as the most common problem with cables is due to signal loss from poor quality cables.

    1D. Eliminate any Middlemen between the Camera and the Computer

If you are using a USB hub you will first have to check both cables with a direct connection between the camera and the computer. Again, it is best to use the cable that came from the manufacturer or at least make sure it is the correct USB type and keep the cable length short.  If the direct connection between the camera and the computer works with both cables the problem is in the hub. 

Once your solve your connection problem make sure to mark the cables and USB ports so that you can connect everything the same way every time.  

2.  Cannot See Anything in the Image

Here we have the camera successfully connected and recognized by our Live Stacking SW, but, after we slew the telescope to the object we are interested to see and take an image the screen is blank.  There are several possible causes for this.  Once again, it is a good idea to shake down your setup during the daytime as much as possible.  This would include focusing on a distant object such as a building, tree, power line or hill side to not only make certain that the camera can provide an image, but also to make certain it is in focus.

​  2A. Check the Optical Path

We have to start with the easiest and obvious root cause, a blocked optical path.  Don't laugh, but I once did forget to remove the dew cap on my scope and it took me a minute to realize that it was what was keeping me from seeing anything.  It is also possible that an object like a tree or a house is blocking light from reaching the scope.  This seems to happen most often when working remotely when one cannot see where the scope is pointing.  The other possibility is a bank of clouds which may have suddenly rolled in.

   2B Check the Exposure

Another easy thing to check is the exposure.   If you are observing from a location with significant light pollution with a short exposure and low gain setting on the camera, stars may not stand out against the bright background.  Raise the gain to maximum and check again.  If the exposure is too short the high gain will make the stars stand out against the bright background.  Once you verify that you can now see stars, lower the gain back down and raise the exposure so that you can still see stars in your image.

   2C. Check the Focus

If neither of those are the cause of a blank image the camera may be so far out of focus so that the light from the stars is so spread out they become impossible to see.  It is possible to be centered on a very bright star but not see anything if the scope is badly out of focus.  This is a more common problem than one might think as many scopes, especially Schmidt Cassegrain telescopes (SCTs), can be used at very different focal lengths.   For instance, the focus points on my 11" SCT when used at f/2 and f/7.5 are nearly at opposite ends of the focus travel.  So, when I switch from one to the other I have to make a very large change in the focuser position to achieve focus.

It can be a challenge to find the proper focus position when the telescope is so far out of focus.  If the mount is not accurately aligned, you won't be sure when you are pointing at a bright star or planet.   The easiest way to solve this problem is to focus on a very distant terrestrial object such as a power pole, tree or hill side during daylight.  Then, at night you will be much closer to focus and should be able to see stars appearing as donuts which you can then bring to focus as sharp points.  If, like me, you cannot see a distant object to focus on from your observing location you will have to wait to focus on the moon at night.  

I find that it is easier to get the telescope pointed at the moon than a bright star, not just because of its size, but also because of its brightness, even when the scope is badly out of focus.  Even if the moon is slightly out of the field of view you will still see a bright glow on the side where the moon located.  Moving the mount in the direction where this bright glow gets bigger and/or brighter will center the moon allowing you to adjust the focus in either direction to see it come into sharp focus.  This is one reason why I find it useful to have a unity finder aligned to the optical path of the scope.  That way, if you are badly out of focus and cannot find a bright star or even the moon in the camera, you can still find and center it with the unity finder and then proceed with focusing the scope.​

​3.  Can See Stars, but Not DSOs

You take a short exposure and you can clearly see a field of stars, but you cannot see that pesky Deep Sky Object you are looking for.  Where is it?  Well there are several possible reasons for its ability to hide from you.

  3A.  Exposure and/or Gain Settings are Too Low
​
All but a few very bright DSOs can be very hard to see due to their low surface brightness and inability to stand out against a bright light polluted background.  After all, this is why we do EAA rather than visual observing.  The first thing to try is to raise the exposure and gain to see if that makes the object magically appear. 

  3B.  Check the Histogram

The object may actually be there but still difficult to see because the black level on the histogram is set too high.  This is unlikely but is something simple to check.  Below is how a typical Histogram should look.  If the black level slider on the bottom left is set too far to the right the image will disappear.

   3C.  Check the Focus

If the focus is off you may have a hard time detecting the DSO.  Focusing methods are not the subject of this blog, but Sharpcap has several focusing aids to choose including both automatic if you have a motorized focuser connected and manual if you do not.  And, there is the tried and true Bahtinov mask focusing technique which is very simple to use.

   3D.  Check the Mount Alignment

If you do not have a good GoTo alignment you may not be centered on the DSO you have commanded the mount to slew to.  You can check this easily by telling the scope to GoTo a bright star in the night sky that you are familiar with.  If after slewing to where the mount thinks the star is you cannot see it in the field of view then you need to do one of several things.  

First, you can re-do the GoTo alignment making sure to use at least three stars and carefully center each star in the field of view.  Most Live Stacking SW has a reticle overlay that can be applied which you should use to center the star as accurately as possible.  Also, it is good practice to center the stars using the UP and RIGHT controls on the mount (either with the hand control or in the SW) to take out any backlash in the mount.  Also, make very certain that you are actually pointing to the stars the mount believes it is centered upon.  If you are not absolutely certain, use a star map or use a different star.  One mis-identified star will mess up the alignment.   With the Celestron Nexstar mounts you don't even need to know the names of the alignment stars, you just have to point the scope at 3 of them and center each and the Nexstar will even tell you the names of the stars.  Another important point when doing a GoTo alignment is to use stars widely separated across the night sky to get the best accuracy in the alignment.

Second, an easy method for letting the mount fine tune its position in the sky is to use the Sync command.  To do this, move the mount to a known star nearby the DSO you are trying to find, center that star and then press the Sync command.  This will let the mount know exactly where it is pointed so that it can have a better chance of putting the DSO in the field of view after the Sync procedure.  For this to work, you must know the name of the star, it must be relatively close to the DSO and you must properly center it before Syncing.  Note, however, that Syncing on a star in one section of the sky may not guarantee that the mount will accurately center DSOs in another section of the sky far away.  You may have to do a second Snyc.  This is where a good GoTo alignment can make finding multiple DSOs in different parts of the sky go much faster.

A third method, which has become very popular these days and may, in fact, be the preferred method for most folks is to use Plate Solving to accurately place DSOs in the field of view.  In simplest terms, the SW commands the mount to slew to the position in the sky where it thinks the DSO should be, takes an image, identifies the positions of the stars in the image and compares these to a database to accurately determine the RA and Dec of the center of the field of view.  If the resulting RA and Dec are not the same as the coordinates of the DSO, the mount moves to the correct coordinates and takes another image.  It solves (Plate Solves) the new image to determine the new RA and Dec and compares these again to the position of the DSO.  It will continue to make small adjustments until the solved RA and Dec are within a pre-determined distance from the desired RA and Dec.  For Plate Solving to work one must have the Plate Solving SW and database(s) installed on the computer along with the correct focal length of the scope and pixel size of the camera.  We will not go into Plate Solving details in this Blog.  The nice thing about Plate Solving is that it doesn't even require a GoTo alignment and it is extremely accurate in centering objects.

Hopefully if you ever encounter one of these three problems you will remember this troubleshooting guide and work through to a solution quickly and painlessly.  In my next Blog installment I will tackle some of the next challenges on my list.

​ 

Celestron's 6.3X focal reducer/field flattener is a very popular accessory for non-Edge SCTs because it reduces the focal ratio of the SCT from its native f/10 to f/6.3.   This increases the field of view (FOV) and increases the optical speed of the SCT as well.  Both effects are helpful for astrophotography and  Electronically Assisted Astronomy as they make shorter exposures possible and allow larger Deep Sky Objects (DSOs) to fit in the camera's sensor.   And because it is also a field flattener it will improve the sharpness of the image at the edge of the FOV.   The same benefits of a wider field and more intense image apply to visual observers as well 

Reducing the focal ratio with this reducer speeds up the optics by a factor of (10/6.3)^2 = 2.5.  It concomitantly increases the FOV by the same amount.  For instance, an 8" SCT with the ZWO ASI533MC camera has a FOV of 19.4 x 19.4 arcminutes at f/10 which increases to 30.8 x 30.8 arcminutes at f/6.3.  That is 376 arcminutes-squared vs 949 arcminutes-squared with the later 2.5X the former.  For the 8" SCT the focal length reduces from 2000mm to 1260mm with the reducer.

Determining the Correct Back Spacing Target
For any focal reducer to work as designed It is important to place the sensor of the camera at the correct back spacing, or distance, from the focal reducer.  This will ensure that the focal reduction will match the design target, in this case 6.3X.  It also ensures that the field flattener works optimally to provide sharp, round stars to the edge of the FOV.  If the camera's sensor is placed closer to the focal ratio will be larger, say 6.5X or 7X, and the focal reduction will be less. If it is placed further from the reducer the focal ratio will be smaller, say 6X or 5X, and the reduction will be more.  In addition, the field flattener will not perform optimally so stars near the edge of the FOV may be distorted.  For astrophotography we want to get the best possible images so we want to be as close to the ideal back spacing as possible.  For Electronically Assisted Astronomy (EAA) we may be less fussy about the edge of the FOV and more interested in speeding up the optical system and/or fitting more of the larger DSOs in the FOV.  In that case a slightly larger back spacing is sometimes used.  Regardless, it is important to know how to get the correct back spacing to begin with.

So, how do we achieve the correct back spacing when using the Celestron 6.3X focal reducer?  We need to know the correct back spacing and how it is measured.  If you search the internet you will find answers ranging from approximately 100mm to 110mm with the most common answer being 105mm.  Surprisingly Celestron has not published a spec for the back spacing for this reducer.  If you also look to find out where on the focal reducer the back spacing measurement is made, this is where you will find the most disagreement.  Some suggest the measurement should be made from the center of the lens' inside the focal reducer (1 in the image above), others from the flat surface on the inside of the threads (2), or the back edge of the threads (3) as shown in the photo.  The correct answer to both of these questions is 105mm from the extreme back surface of the focal reducer as shown in the photo identified as location 4 in red.  So how do we know that these are correct?

First, we know that the industry standard back spacing for focal reducers used on refractors is 55mm (there are some exceptions).  Second, because the optics of an SCT is very different from a refractor it is not possible to make a focal reducer for an SCT with a back spacing of 55mm.  So, Celestron did the next best thing.  They made an adapter which attaches to the back of the focal reducer and is exactly 50mm long.  This leaves the industry standard 55mm left to obtain the correct back spacing of 105mm.  Also note that the 50mm length of this adapter is measured from the the flat surface of the flange which mates with the surface "4" in the image above to the flat surface on the other end of the adapter not including the threads where the next spacer will bottom out when screwed all the way on.  Similarly, Celestron makes a 7X focal reducer for their Edge SCTs and in this case they do specify the back spacing as 146.05mm.  And likewise, they make a T-Adapter to attach directly to this focal reducer which is 91mm long leaving 55.05mm of additional spacing to meet the back spacing spec.  So, I think it is clear that the design back spacing for the 6.3X reducer is 105mm and not 100mm, 110mm or something else, and that it is measured from surface 4 on the focal reducer.

Imaging Train Options for the 105mm Back Spacing
Now that we have established that we need 105mm of spacing for the Celestron 6.3X reducer we need to figure out what options are readily available.  But first, we need to take into account the back spacing of the camera sensor itself.  This can be found from the manufacturer and we will use ZWO's ASI cameras as an example.  Below is ZWO's mechanical drawing for their ASI2600MC camera.  This shows the position of the CMOS image sensor relative to the front surface of the camera to be 17.5mm.  Likewise the ASI585MC has a back spacing of 17.5mm for the sensor even though it uses a different coupler on the front face.  If you look at most cameras these days from ZWO and other manufacturers you will find that 17.5mm is the most common back spacing for the sensor.  However, be careful to check as the ASI224MC shown below only has a 12.5mm back spacing.​

Like plumbing or garden irrigation systems there are many different spacers and adapters available such that one can find many combinations of such to make up the additional back spacing needed.  After searching through multiple astronomy supplier's sites I have come up with what I believe to the be the least complicated solutions using the simplest set of adapters available to achieve the 105mm back spacing.   I list the parts needed below along with links to either Agena Astro or HighPoint Scientific, two of my goto astronomy suppliers.  Links are affiliate links which will earn a small commission at no cost to you.  Please use these if you can to support my web site.

From Agena Astro
Celestron 6.3X focal reducer
Celestron 50mm SCT-T Adapter
Blue Fireball 37.5mm Extension
ZWO 11mm Female to Female Adapter

If you want to fine tune the spacing you can use Baader T2 Delrin spacers to adjust the spacing in small increments from 0.6 to 1.4mm.  If you want to make larger spacing changes you can search for the desired M42/T2 spacer from  Blue Fireball, or substitute the Baader Varilock 46 T2 Variable Extension in place the 37.5mm Extension listed above for greater versatility.

Here is an almost identical solution from HighPoint Scientific.  Since they do not list a 37.5mm spacer it uses a 30mm and 7.5mm spacer which are sold together as a kit from Celestron.

From HighPoint Scientific
Celestron 6.3X focal reducer
Celestron 50mm SCT-T Adapter 
Celestron M42 Spacer Kit  (30mm + 7.5mm)
ZWO M42 Female to Female 11mm Adapter 

Alternatively to the Celestron M42 spacer kit one could substitute the Baader Varilock 46 T2 Variable Extension which, while almost twice as expensive, allows for variability in the spacing.  Also the Baader T2 Delrin Spacer Ring Set is an option for fine tuning the spacing on the order of a mm or less.

Back Spacing Solutions With a Filter Drawer
Now if we want to use filters with our camera we can put a filter drawer in line so that it is easy to change filters in real time.  In this case we will need some different spacers and adapters.  Also, we need to take into account the fact that the glass of the filter has a different index of refraction compared to air.  Filter glass is typically 2-3mm thick so we need to add ~1/3 of that thickness to our optical path for an additional ~1mm.  Below is the same setup as above showing the parts needed along with links to either Agena Astro or HighPoint Scientific.

Agena Astro
Celestron 6.3X focal reducer
Celestron SCT-T Adapter
Blue Fireball 10mm Extension 
Blue Fireball 7.5mm Spacer Ring 
ZWO M42 11mm Female to Female Adapter 
ZWO Filter Drawer M42 Male to M48 Female 
ZWO M48 Male to M42 Female Adapter 

HighPoint Scientific
Celestron 6.3X focal reducer
Celestron SCT-T Adapter
Apertura10mm Extension 
Baader 7.5mm T-2 Extension
ZWO M42 11mm Female to Female Adapter
ZWO Filter Drawer M42 Male to M48 Female 
​ZWO M48 Male to M42 Female Adapter 

​Back Spacing Solutions for SE/Evo/CPC Mounts at 90deg Altitude
The solutions above work with cooled and uncooled cameras on any Equatorial mount.  In the case of a single arm Alt-Az mount like the Celestron SE or Evolution mounts, or a dual arm mount like the CPC mount, the solutions above will only work as long as the OTA is not pointed higher than ~75 degrees in altitude.  Higher altitudes will cause the camera to crash into the base of the mount.  A simple solution to reach an altitude of 90degrees without hitting the mount is to add a rail extension along with the imaging trains shown above so that the OTA can be pushed forward to provide enough additional clearance.  An inexpensive rail extension is available from SVBony which will work on the 6" SCT.  The longer Celestron Universal Mounting Plate is probably a better option for the 8" and 9.25" SCTs and is available from both Agena Astro and HighPoint Scientific.  If using a cooled camera there will not be enough room to push the OTA forward and a different approach is needed.  This approach uses a diagonal to place the camera at a right angle to the optical axis to gain additional clearance.  The details of this configuration can be found in the equipment recommendations section of this web site here.

If you would like to see all of these configurations in action, please take a look at the video I put together on this subject where I demonstrate each solution in detail.  The video is on my YouTube channel here where you can also find other helpful videos for the amateur astronomer.

All links are affiliate links which can earn a commission without any additional cost to you.  Please consider using them to help support this channel.

Talentcell sells a line of small and light weight portable power banks which have become very popular among amateur astronomers over the years.  Their easy portability means that they can be carried out to a dark sky location or taken to public outreach events to provide limited power without the added burden of a larger capacity battery.  It also means that the power bank can be attached to the telescope mount or optical tube to minimize cabling.  Advertised on Amazon as 12V batteries Talentcell's power banks are available at prices ranging from $26 for their 3Ah model to $88 for their 12Ah model which can really help to keep the cost of portable power low.   One should expect that even the smallest capacity power bank should be enough to power a modest sized mount like a Celestron SE Alt-Az or AVX EQ mount, or a Sky-Watcher Star Adventurer along with a few accessories for several hours.  I have used their 8.3Ah model to power a Celestron 6SE along with an analog video camera and 10" LCD when doing EAA at public outreach events.   

I suspect that hundreds, if not thousands of amateur astronomers have been using these power banks for years completely unaware that they actually are not 12V batteries at all and do not even supply 12V once a load has been applied.  I count myself as one so unaware for many years until I started seeing complaints on CloudyNights about problems using these Talentcells to power ASIAIR computers or ZWO AM3 and AM5 mounts all of which had a problem with the actual voltages supplied by the power banks.  This prompted me to take a detailed look at the design of the Talentcell power banks.  I eventually purchased 3 more Talentcells to run through extensive testing along with my original 8.3Ah model to demonstrate for myself that these are not really 12V batteries and do not provide an output voltage of 12V except when no load is applied.

It is important in this discussion to distinguish between the many Talentcell power banks which are advertised as "Lithium ion" or "Li-ion" batteries versus the 2 Talentcell models which are advertised as "LiFePO4 Battery Packs".  Of the former I count at least 9 different models being advertised on Amazon as of this writing versus 2 models of the later identified as "LiFePO4 Battery Packs".  So what are the differences between these 2 different types?  First, the 9 models advertised a "Lithium ion" use LiNiMnCoO2 as the internal power cells.  LiNiMnCoO2 (NMC) is a very common Lithium Ion cell used in many applications, primarily where weight is a key concern such as in ebikes, electric power tools, some models of electric cars including many models of the Tesla, and in most of the portable power stations like the Jackery sold to date.  NMC is considered one of the safest Lithium cells with a thermal runaway temperature second only to LiFePO4.  Power supplies with NMC cells are usually rated for ~500 full discharge cycles after which 75 - 80% of the original capacity remains.  In contrast power supplies with LiFePO4 are rated at 4,000 or more full discharge cycles which is why these are found in the batteries used in RVs and boats.  LiFePO4 cells are now beginning to show up in portable power stations from Jackery and others.

The other main difference between NMC and LiFePO4 cells, and one of the keys to understanding the problem with many of the Talentcell power banks, is their nominal cell voltages.  NMC has a nominal cell voltage of 3.6 to 3.7V.  That means when fully charged it has a useable energy capacity starting at 3.6 or 3.7V.  On the other hand, LiFePO4 has a nominal cell voltage of 3.2V which actually makes it an ideal lithium cell type for creating a 12V battery as 4 of the LiFePO4 cells in series will provide 12.8V.  On the other had, 4 NMC cells in series will provide 14.4 to 14.8V which is too high for a typical 12V system.  This is why a Jackery portable power stations using NMC cells have an internal voltage regulator to keep the output voltage in the 12V to 13.2V range throughout 100% of its depth of discharge (DOD) at which point the internal BMS shuts down the output.  In contrast, a 12V battery using LiFePO4 cells does not need a voltage regulator so its voltage remains above 12.0V throughout 95% of its DOD.  The voltage versus capacity curves shown above for LiFePO4, LiNiMnCoO2 and a lead acid battery demonstrate this quite clearly.

​So why do I say that the Talentcell power banks using NMC cells are not 12V batteries?  To understand this we need to take a look at the design of these power banks.  Here we have Talentcell's own advertised design information which shows that they are using 3, not 4, NMC cells in series and then adding multiples of these in parallel to increase the capacity as needed.  Here is an image of their 6Ah design which has 6 total cells configured as 2 parallel banks of 3 cells in series.  The 3 cells in series can only produce 3 x 3.7V = 11.1V , not 12.8V.  Interestingly, if you look closely at Talentcell's own specifications you will see that they indicate 11.1V 6000mAh for the capacity in the technical details for this battery, not 12V 6000mAh.  (6000mAh is 6Ah).  Yet, looking into the technical details you will see the output rated at a voltage range of 12.6V-9V.  So where do they get 12.6V from?  Well, let's take a look at the discharge curve for a LiNiMnCoO2 cell from Panasonic. These curves are for different discharge currents but each shows that while the cell can be charged to as much a 4.2V, the voltage drops below 4.0V, even to 3.7V depending upon the discharge current, as soon as a load is applied.  With no load applied, 3 cells at 4.2V will show a voltage of 12.6V which is what the Talentcell spec is referencing.  But with even a small load the voltage drops immediately below 12V because there is essentially no capacity in the cell above 3.7V.

To confirm all of this I purchased 2 of the power banks utilizing the 3S design with NMC cells, a 6Ah and a 12.8Ah version added to the 8.3Ah version I already had.  I also purchased a 6.5Ah Talentcell power bank using 4 LiFePO4 cells in series for comparison.  I ran each of these through a full discharge cycle test after first fully charging them per the manufacturer's instructions.  

The measured capacities for each power bank are shown in the accompanying table.  I used a load current at least half the rated current for each power bank in the capacity test to avoid stressing the battery.  In the case of the 6Ah power bank I also used the maximum rated current of 3A to see if the measured capacity differed.  Only the power bank with the 4S design using LiFePO4 cells met the rated capacity while the other 2 new power banks fell short by 5 and 15% respectively.  I did not expect my 6 year old 8.3Ah power bank to match the rated capacity since I did not care for it well over its lifetime.  More important than the rated capacities is the voltage versus capacity curves which are shown in the graph below.  There are two curves for the 6Ah power bank since I measured this at both 1A and 3A loads.  The curves show that while the no load voltage is 12.6V per the spec, the voltage drops below 12.0V as soon as a load is applied.  For all 3 power banks the voltage drops below 11V with 70% of their rated capacity left which is quite amazing for a battery sold as a 12V battery.  While lots of 12V equipment, including our typical astronomy gear, has a wide voltage tolerance, they are not designed to operate optimally when the voltage drops this low.  This is clearly why the ZWO ASIAIR and AM3 and AM5 do not like these power banks.  Even more amazing is the fact that these batteries drop below 10V with 30% of their capacity remaining.  Even if your equipment works down to 10V, you are not getting the capacity you are paying for with these power banks.  Looking at the 3A load curve for the 6Ah battery we can see if we push to the maximum current of the power bank the voltage drops even more precipitously and we can expect our equipment to quit or, at least, complain much sooner.

So, why is this happening?  Well I can only guess as to the reason that Talentcell uses a 3S design with these 9 different 12V power banks.  First, with less cells they save space and weight which helps to keep the power banks small and portable which is their main selling feature.  Also, by not using a 4S design they save on the cost of additional cells and the cost of the voltage regulator that would be required to drop the voltage into a typical 12V power supply range.  It is the simple fact that they use 3 cells in series and not 4 with a voltage regulator that these are not really 12V power banks.

On the other hand, the 4S designs with LiFePO4 perform perfectly as expected for a 12V battery and are the only ones that I recommend.  As the voltage versus capacity curve below shows, the voltage stays above 12V for about 90% of its rated capacity with a load of 2A which is ~36W of power.  If you push the power bank to its maximum current capacity of 5A the voltage drops more quickly but stays above 12V for ~66% of capacity and doesn't drop below 11V for 95% of the total capacity.  Talentcell currently has one 4S model which uses LiFePO4 cells and has  a capacity of 6.5Ah, which is model that I bought and tested and which be can found here. And if you need more capacity than that, here is a 12Ah LiFePO4 battery from Talentcell which is not a power bank but is still small enough to fit in the palm of a hand.  ( Links are affiliate links).

Talentcell is not the only one using a 3S design in their "12V" batteries.  A short survey on Amazon found several other manufacturer's of power banks doing the same thing.  And, amazingly to me, I found that even some of the portable power stations available such as the EBL 300Wh model specifies a DC output voltage of 9 - 12.6V just like the Talentcells with a 3S design while the EBL models 500 and 100 (which I tested and reported on here) specify a DC output voltage of 11.8 to 14V which is consistent with a 4S design with NMC cells and a voltage regulator.  So my suggestion is to look carefully at the specifications before you buy.

If you want to see more on this topic, I made of video showing exactly how I tested the 4 Talentcell power banks which I bought and which you can find on my Youtube channel. 

These are the only TalentCell power banks that I would recommend, along with a 12Ah LiFePO4 battery if you need more power.  Links are affiliate links which can earn a commission without any cost to you and help support this web site.

Talentcell 12V LiFePO4 Battery 12.8V 6.5Ah 83.2Wh -  amzn.to/3NYIPxD
Talentcell 12V LiFePO4 Battery 153.6Wh 12.8V 12Ah:  amzn.to/3SfDMM0

If you own a Celestron SCT and do not already have a hyperstar adapter you should.  What is hyperstar?  It is a multi-element optical adapter which converts the focal ratio of an SCT from its native f/10 to f/2.  Since the optical speed of a telescope is proportional to the square of its f-ratio, adding a hyperstar will increase the speed of an SCT by a factor of 25:  speed ~ (10/2)^2 = 5^2 = 25.  My first experience with hyperstar was back in 2015 when I first tried it on my 14" SCT to capture a breathtaking view of NGC253 the Sculptor Galaxy in just 22seconds.  I was just blown away by what the hyperstar was able to capture in such a short time.  Of course, smaller aperture telescopes will not produce such an image in the same time, but they will still have 25X faster optics resulting in amazing images in short times of their own right.

Hyperstar is available for the 6", 8", 11" and 14" Celestron Edge and non-Edge SCTs and the 9.25" Edge version.  It has been available for these models for some time.  Just check the front of the Secondary mirror for the phrase "Fastar", where Fastar is the original Celestron name for this, to see if your older model is compatible.  For those that do not say "Fastar" a conversion kit is available for all 6" through 14" models except the 9.25" model.

How does hyperstar work? 
An SCT consists of three optical elements, a corrector plate at the front, the primary mirror in the back and the secondary mirror in the center of the corrector.  SCT primaries are spherical mirrors configured to a focal ratio of f/2.  Actually the focal ratio of a Celestron SCT primary varies between f/1.9 and f/2.3 depending upon the model as shown in the accompanying table.  For the sake of simplicity, lets stick with f/2 as our example.  The secondary mirror is figured to a focal ratio of f/5 so the combined effect is a focal ratio of f/10, f/2 x f/5 = f/10.

​Hyperstar is installed by removing the secondary mirror and replacing it with the hyperstar compound lens.  With no secondary the focal ratio is that of the primary mirror, or f/2.  Obviously the hyperstar element can only be used with a camera for imaging, either for traditional astrophotography or electronically assisted astronomy, and not for visual observations.  A camera is attached to the hyperstar via an adapter which is specific to the camera and hyperstar size.  The light enters the SCT through the front corrector plate and reflects off the primary mirror just as it always does.  But now, instead of reflecting off the secondary mirror back through the center of the primary and out the back of the SCT, it travels through the optical elements of the hyperstar and into the camera.  

​The hyperstar is a multi-element lens/corrector which not only focuses the light onto the sensor in the camera, but also corrects for the spherical aberrations and field curvature which would be present without the corrective capability of the hyperstar.  Images taken with the hyperstar should be sharp and flat across the field of view.  

Hyperstar can be used for both traditional astrophotography and electronically assisted astronomy.  In both cases, the faster focal ratio enables more light to be collected in a given time compared to the SCT's native focal ratio of f/10.  The results can be stunning as in the traditional astro photo of M31 shown below taken on a C11 with hyperstar for a total exposure time of 213 minutes using Pixinsight to combine and process hundreds of sub-frames.  Similarly, amazing results can be obtained during live stacking and viewing during an EAA session as seen in the image of the Rosette Nebula taken with TSX's Live Stack feature stacking and stretching 120 x 5 sec sub-frames for a total of 10 minutes also using a C11 with hyperstar.​

​Using Hyperstar
The hyperstar adapter has 3 thumbscrews which are designed to allow 360 degree rotation of the hyperstar so that you can adjust the orientation of your camera.  Just loosen all three thumbscrews 1/4 turn, rotate the the outer body of the hyperstar to the desired orientation of the camera.  Then tighten the thumbscrews to lock the camera orientation.  Since these thumbscrews hold the two halves of the hyperstar together, you should never completely remove them.
USB and power (if needed) cables are attached to the camera as usual.  If you are using a dew shield you can either bring the cables out the front of the shield or, out the back of the shield if it has a notch in it.  In either case tie off the cables so they do not drag.  In some cases, the cables may produce diffraction spikes on bright stars just like the spider vanes on a Newtonian secondary.  This can be minimized by avoiding running the cables in a straight line across the front of the OTA.

The hyperstar camera adapter is threaded inside so that a filter can be attached.  This works well if you intend to use only a single filter, such as a light pollution filter, a UV-IR filter or a multi-band filter during you imaging session.  Just unscrew the front piece on the adapter, screw in the filter and screw the adapter/filter combination back on.  Then attach the camera.

If you want to change filters during a session you will need a filter drawer for the hyperstar.  The filter drawer screws onto a separate hyperstar adapter such that the combination provides the correct backspacing for your camera.
​
Everything else in an imaging or EAA session will be the same as if you did not have the hyperstar except it will require much less time to be able to see DSOs compared to operating at f/10.

Wide Field
Since the hyperstar reduces the focal ratio to f/2 but does not reduce the aperture of the telescope, the field of view will be much wider.  In fact, the field of view will also be 25X larger compared to f/10, 5X in each axis of the camera sensor.  This is precisely how the hyperstar speeds up imaging.   To understand this let's take a look at the difference in image scales at f/10 and f/2.  Image scale depends upon the size of the pixels in the camera and the focal length of the telescope.  It is defined by the following equation:

   Image Scale (arc-sec/pixel)  = 205 x pixel size (microns) / focal length (mm)

So, for the same camera, the image scale varies inversely with the focal length.  In other words, the image scale increases as the focal length gets smaller.  Adding the hyperstar reduces the focal length proportional to the reduction in focal ratio.  For the C11 discussed above the focal length is reduced from its native 2794mm to 559mm with hyperstar.  The image scale is then reduced by the same factor of 5 across the x and y axis of the camera chip.  This means that each pixel is collecting light from an area of the sky 25X larger with the hyperstar than without the hyperstar which is why the exposure time is reduced.  Keep in mind that with the wider field of view the resolution is now reduced by the same amount.  But since seeing conditions usually dominate image resolution stars and most CMOS cameras used for astronomy have sensors with pixels smaller than 4microns on a side the image quality will still be excellent, even if you zoom in on the image.

Summary
Hyperstar is certainly expensive costing just under $1000 for an 8" SCT and more for larger apertures.  However it should be viewed as turning your f/10 SCT into a completely new telescope with a focal ratio at least 4X faster than the fastest refractors available while maintaining an aperture many times larger than a refractor.  Think of it as investing in an entirely new scope but without having to purchase a new set of accessories (finder, dew heater, focuser, etc.).  As the few images shared here show, hyperstar can produce incredible images in real time and is well suited to capturing more of the larger DSOs.

If you want to see more about the amazing hyperstar check out my hyperstar YouTube video 

Links are affiliate links which can earn a commission without any cost to you.  Please consider using them to help support this web site.  

Hyperstar is available from HighPoint Scientific bit.ly/3RO8vgv

I have previously reported on my results testing several different portable power stations from Jackery, EBL and Bluetti along with LIFePO4 batteries from Li Time (formerly Ampere Time), Bioenno Power and Battleborn to power my astronomy rig out in the field.  Typically we travel to distant dark sites for multiple nights under the stars and most likely will need some way to recharge a power station or battery during the day.  Portable solar panels are a great way to do this when AC power is not available.  So in this blog I will review three 100W portable solar panels that I have been using over the last few years.  While the panels were sent to me by their suppliers at no cost to me I am under no obligation to provide a positive review and/or avoid negative comments if they are warranted.  None of the suppliers has seen this review before it was posted.  So here we go.

The three solar panels are the Jackery Solar Saga 100, the EBL Solar Apollo 100 and a 100W panel from Bioenno Power.  Each is designed for a maximum of 100W of output power, but anyone already familiar with solar panels know that the 100W specification is only achieved under ideal laboratory conditions with a well controlled and uniform light intensity at the optimum angle and at room temperature.  In real world conditions, expect to get ~70 to 90% of the specified maximum rating out of any solar panel.  All 3 of the panels in this review use monocyrstalline silicon photo voltaic chips which are the most efficient solar panels on the market with an efficiency of 24%.

Jackery Solar Saga 100
The Jackery Solar Saga 100 is highly rated but is one of the more expensive panels at $269 as of this blog.  The Jackery has an output voltage of 18V at 5.55A which works out to 99.9W.  The panel is fairly large with an unfolded dimension of 48" x 21".  When folded it reduces to 24" x 21" and 2" thick which makes it fairly easy to pack away for travel.  It has convenient built in carrying handles and magnets to help keep the two halves together when closed.  Jackery claims that the panel weighs only 5.5lbs but I measured it to actually be 9lbs, which is considerably more but not difficult to carry around.  A big plus of the Jackery compared to the other panels is the two large, 6.25" wide, kickstands which make it easy to set up and keep both halves of the panel at the same angle to the sun.  The panel is coated with a plastic material to make it more durable and easier to clean and is splash resistant but not waterproof.  I found the overall build quality to be quite good and the panels (I have 2 of them) have stood up quite well to occasional use over the last 2+ years.

The electrical connection is inside a zippered case and includes a single 10ft long 16AWG cable with an 8MM male plug designed to be plug compatible with Jackery's portable power stations.  If you have another brand of power station which does not use the 8mm connection you can get an adapter to connect the Jackery panel to it.  I like the fact that they provide a long cable which allows flexibility in positioning he power station or battery being charged.  It is best to keep the power station or battery from direct sun exposure and I typically place it behind the panel.  I also like the fact that the input cable is strain relieved at the point that it connects to the panel.  There are two USB ports ( 5V/3A USBC 5V/2.4A USBA) at the strain relief which allow direct charging of USB devices by the panel such as your phone, laptop, tablet, camera, etc.  The Jackery solar panel comes with a 2 year warranty and technical support is available in Fremont, California so you do not have to email China for help.  I will note that one of the 2 Jackery panels sent to me did fail after about 1 year of use for no apparent reason and was promptly replaced with a new panel.  

Bioenno Power
The Bioenno Power solar panel is designed very differently from the other two panels.  It is a quad -fold panel which means that it folds down to a much smaller package measuring 20.5" x 14.5" which makes it easier than either of the other two panels to pack in a smaller space.  Unfolder it is the longest of the panels at 57" x 20.5".  I found the two 2" wide kickstands totally inadequate to set up the panel so that all four segments are aligned in the same plane.  This would be much better if that had 3 or 4 kickstands at least 3" wide.  It also has a convenient carrying handle and clips to hold the panel shut. The Bioenno panel weights slightly more than the other two at 10lbs.   This panel is priced between the other two at $210 and it has an output voltage of 18V with 5.56A.

Just like the other two panels the cable sits inside a zippered compartment.  Unfortunately, the cable is even shorter than the one provided by EBL which means that you will definitely need to buy an extension cable to have any practical chance to connect the panel to a power station.  But, since the Bioenno Power uses a non-standard 50A Anderson Power Pole connector you would certainly need an adapter cable anyway.  Bioenno Power sells an adapter cable which converts to the much more common 40A Anderson Power Pole connector.  Like the EBL the Bioenno Power does not have a USB charging port but does have a solid strain relief like the Jackery . 

Charging Tests
I performed two different charging tests on each panel.   The first test was designed to determine the maximum output power of each panel on a clear sunny day in June with the sun at its peak in the sky for the day.  Each panel was supported by a piece of plywood to hold it flat in a plane and tilted in altitude and rotated in zenith relative the the sun until a maxim input reading was obtained on a Jackery 1000 portable power station's input meter.   The Bioenno Power produced the highest maximum output of 89W, while the Jackery had a maximum of 83W and the EBL panel produced the lowest power output of 72W.  As discussed in the beginning we see clearly that the outputs are not 100W.  The Bioenno Power panel outperformed the other two with the outputs of the Jackery at ~93% and the EBL at only ~81% of the Bioenno Power's output.

​The next test was a 3 hours cumulative power output test.  Here I measured the output power produced over a 3 hour period on a clear sunny day in June starting 1.5 hours before the sun peaked in altitude through 1.5hrs after the peak.  Thus the panels were exposed to the maximum solar radiation possible on that day.  To measure the output power I used identical in-line DC power meters which measure the power, voltage, current, Ah and Wh produced.  I needed something for the solar panels to charge during the tests but I did not have 3 identical power stations which would have made the test very simple.  Instead, I used my Jackery 1000 and EBL 1000 portable power stations as the loads with the DC power meters between the panels and the power stations.  Since the charging circuits on the two power stations may behave differently I had each panel charge each of the two power stations for half the 3 hour time so as to accommodate any variation in power because of differences in the power stations.  So each panel charged each power station for 1.5hrs during the test.  Now, 3 panels into 2 power stations does not divide evenly.  So, I ran the test in pairs, testing all three combinations of pairs over 3 days with clear skies from 11:30AM until 2:30PM swapping power stations and in-line meters at the midpoint of 1PM.

Test Order:
Day 1:   Jackery Solar Saga vs. EBL Apollo
Day 2   EBL vs Bioenno Power
Day 3   Jackery vs. Bioenno Power

​The results are shared in Table 2 below which shows that the Jackery produced 35Wh, or 16%, more energy than the EBL Apollo over the 3 hours on day 1.  The Bioenno Power panel produced 32.5Wh, or 18%, more energy on day 2 than the EBL panel.  And on day 3 the Bioenno Power Panel produced 9.7Wh, or 6%, more energy than the Jackery solar panel.

Now, to be fair, even though the measurements were done at the same times on all 3 days, and even though all 3 days were clear sunny days, we cannot be certain that the flux of photons was the same each day.  But there is a way to correct for any differences in the amount of solar radiation over the 3 days.  We can normalize the numbers to the one of the panels on one of the days, in this case, the Bioenno Power output on Day 2.  Since we have each panel tested on 2 days we can take advantage of the readings on the same panel from day to day to correct for differences in solar radiation.

If we take the ratio of the Bioenno Power reading on Day 2 to Day 3 we get 121.1 / 117.6 = 1.03, which means that the solar radiation on Day 2 was 3% higher than on Day 3.  Next we can scale the EBL measurements from Day 2 and Day 1 to get 101.4 / 94.5 = 1.07 which shows that the solar radiation on Day 2 was 7% higher than on Day 1.  Using these Solar Intensity Correction factors we can scale the Day 1 and Day 3 readings to the readings on Day 2 using 1.07 to scale Day 1 and 1.03 to Scale Day 3 as shown in Table 2.

The result is the corrected Table 3 shown below.  This shows that the panels collected a total of 392 to 471 Watt-hours of energy over a 6 hour period of peak solar intensity.  The Bioenno Power panel collected the most energy at 471Wh.  If the panel had actually output 100W during those 6 hours we would have expected 600Wh of energy.  Instead, we got 78.5% of the ideal expectation.  Now keep in mind, the panels lay flat on the ground so they we not at the optimum angle to the sun throughout the data collection period.  I am certain if I had tilted the panel for its maximum output and adjusted it multiple times over the course of the 6 hour test we would see something in the high 80% range as we saw in the maximum output test above.  
The Jackey panel produced less energy over the same time at 441.5Wh which is just under 94% of what the Bioenno Power produced.  This is very consistent with the maximum output test discussed above.  The EBL panel came in significantly behind the other two panels at 392.2Wh which is only 83% of what the Bioenno Power panel produced.  This is also in line with the maximum output test.  

Out of curiosity I measured the area of the solar cells on each panel and found the following:

Jackery Solar Cell Area:                   820 sq-inches
EBL Solar Cell Area:                         950 sq-inches
Bioenno Power Solar Cell Area:     951 sq-inches

I was not surprised to see that the area of the Bioenno Power panel is greater than that of the Jackery.  The ratio of the areas is 86% which explains why the Bioenno Power produces more output than the Jackery, although I am surprised that the Jackery puts out 93% of the power of the Bioenno panel given the size differential.   What surprises me more is that the EBL panel has the same collection area as the Bioenno Power panel, yet it produces only 83% of the power.  While all the panel manufacturers claim efficiencies of 24% we see that the overall efficiency of the Jackery appears to be higher than the other 2.  If we divide the output in Table 3 for each panel by the measured solar cell area we get:

Jackery :    0.54Wh/sq-inch
EBL:           0.41Wh/sq-inch
Bioenno:   0.50Wh/sq-inch

 Summary
The Bioenno Power panel is the clear winner in terms of output and overall compactness of design.  Its only detractors are the two small kickstands which are not quite ideal for the length of the unfolded panel and the short cable with the non-standard connector.  Although the Jackery produced slightly less output compared to the Bioenno Power panel the design is easier to handle with just two panels instead of four, wide kickstands for excellent support, a long and flexible output cable long and USB charging ports.  The output of the EBL panel is quite surprising given the area of the solar cells.  While the panel is much less expensive than the other two, both the lower output power and lack of an adequate strain relief on the cable input to the panel makes this panel much less attractive.

You can find a video version of this review on my YouTube channel here www.youtube.com/watch?v=0LmzAM98sAQ

​Amazon links above are affiliate links which can earn a small commission at no cost to you.  Using these helps to support this web site.

Jackery 100W Solar Panel   amzn.to/3rR3wmZ
EBL 100W Solar Panel   amzn.to/3s1wtMX
​Bioenno Power 100W Solar Panel   www.bioennopower.com/collections/solar-controllers/products/bioenno-power-bsp-100-lite-model-100-watt-foldable-solar-panel

Lithium based power sources like Li ion batteries from Li Time, Bioenno Power and Chins along with portable power stations from companies like Jackery, EBL and Bluetti are quickly replacing lead acid batteries when it comes to powering astronomy setups away from AC power.  Lithium batteries offer several important advantages over traditional lead acid batteries.  First, they have much higher energy densities making them half the weight of a similar capacity lead acid battery.  Second, while lead acid batteries should not be discharged more than 50-60% of their rated capacities to avoid damage including loss of capacity and ultimately complete failure, lithium batteries can safely be fully discharged without damage  (more on this later).  Third, while the voltage of a lead acid battery falls off steeply with depth of discharge, reaching ~12.05V  at 50% DOD, lithium batteries have a much flatter voltage vs SOC curve dropping below 12.0V at ~95% DOD.  Fourth, lithium batteries have a low self discharge rate of 2-3% per month which means they only need to be recharged once every 3-6 months when in storage.  Also, Lithium batteries do not suffer from the memory effect of other battery chemistries so it is not necessary to fully recharge them after use.  Finally, lithium batteries will supply more of their rated capacity in cold temperatures compared to lead acid batteries with some estimates indicating as much as 2X the capacity compared to lead acid below 32F.
​
However, with this new source of energy comes a lot of confusion and downright wrong information on the astronomy forums.  To correct this misinformation I decided it was time to provide a review of the basics of lithium battery technology and to correct the most common misconceptions that I see posted on these forums.  Over the last three years I have immersed myself in lithium technology by both doing a literature search on the subject and by talking directly with multiple suppliers of lithium batteries and power stations to gain a fuller understanding of the technology and manufacturing methods.  I visited the Battleborn factory technical team and toured the factory floor to see and hear how they design, test and assemble their batteries.  Most importantly, working with multiple suppliers I have conducted my own testing of LiFePO4 batteries from 6 different vendors to collect data for myself to compare to manufacturer's specifications and to test out some common misconceptions.  This Blog is a summary of the entirety of my efforts in this regard.

Lithium Batteries vs Power Stations
When it comes to Li ion power there are two very different options.  The first is a stand alone Li battery which is designed and packaged to replace a lead acid battery.  As such, it looks identical to a lead acid battery with the lithium cells enclosed in an ABS case similar in size to an equivalent capacity lead acid battery.  It has a positive and negative terminal just like a lead acid battery.   As described above, the Li battery also has a BMS to provide for safe operation and long life of the battery.  Stand alone batteries use  LiFePO4 and come in many different capacities from a few Ahs to hundreds of Ahs.

The second Li power option is a Li ion power station.  A power station not only provides 12V dc power, but also has an internal pure sine wave inverter to provide AC power via one or more outlets.  It also has multiple powered USB ports to charge phones, tablets and even laptops.  All portable power stations that I have seen come with a cigarette output port with a maximum current of 10A.  Some come with additional dc power ports with a variety of connector types (5.5 x 2.1mm, 5.5 x 2.5mm, 6.5 x 4.1mm, etc.) usually rated 3A - 7AA.  Power stations come with an AC charger to recharge the device from a wall outlet.  They also have an internal solar charge controller which accepts input from one or more solar panels (not typically included) to recharge the power station via the sun.  Power stations include an internal meter and display to show the state of charge (SOC) and power during discharge and recharge operations.  Power stations also have an internal BMS which performs the same functions as in the LiFePO4 battery.  Like the stand alone LiFePO4 battery discussed above, power stations come in a variety of capacities typically stated in Wh from ~200 to over 2k Wh.  Most power stations use LiNiMnCoO2 cells due to their higher energy density which helps keep the weight down since power stations are meant to be portable devices.  There are however, several power stations which use LiFePO4 cells.  With LINiMnCoO2, the dc output is regulated since, as discussed above, the cell voltages do not add up to 12.8V like they do with LiFePO4. 

Lithium Ion Cycle Life and Calendar Life
One of the biggest myths of Li ion batteries is the one which says you cannot discharge a Li ion battery more than 80% or 90% without damaging it.  This is patently false.  Li ion batteries and power stations are designed to be fully discharged.  That means you have access to 100% of the rated capacity without risk of damaging the individual cells inside and without degrading the rated number of discharge cycles of the battery or power station.  For instance, if you check the web sites for Battleborn, Ampere Time (re-branded as Li Time), Chins or Lithionics you will see that they all specify their cycle life in terms of 100% depth of discharge (DOD).  Battleborn specifies 3-5K cycles, Ampere Time 4K + cycles, Chins 2K+, and Lithionics 2K cycles.  And, after that the battery will still retain 75 - 80% of its original capacity.  In the power station category Jackery with LiNiMnCoO2 cells specifies >500 full discharge cycles after which one can expect 80% of the original capacity.  In contrast, as most people know, a lead acid battery should not be discharged below 40% of its capacity otherwise sulfates will form on the plates reducing capacity and eventually shorting out the cells.  In contrast, the BMS inside Li ion batteries monitors the individual cell voltages inside to make sure that no cell's voltage drops below the minimum value shown in the table above, typically 2.5V.  When any cell reaches the minimum the BMS shuts the battery down to prevent cell damage.  So the battery is designed to provide its full rated capacity without any cell's voltage dropping below this safe minimum voltage.  Now it is true that you can extend the cycle life by not fully discharging a Li ion battery.  For instance, discharging a Li ion battery to only 50% DOD can improve the cycle life by almost a factor of 3.  But then you would need to purchase and handle two batteries instead of one to provide the power you need for your equipment.​  A good compromise might be to size the battery you purchase such that you only need to discharge it by 80% - 90% just to be on the conservative side.

Calendar life of a battery refers to how long it will last if stored under ideal conditions of state of charge, temperature and humidity.  This is independent from cycle life.  Typical calendar lifetimes are quoted as 10 years, although Li ion batteries have not been around long enough for a significant amount of data to be collected to confirm this estimate.  By contrast, the calendar life of a lead acid battery is usually quoted as 4 -6 years.  The main mechanism for calendar aging is the growth of passivation layers at the interfaces between the electrolyte and the cathode and anode.  This growth depletes the amount of available cyclable lithium.  Both high temperatures and high SOC can accelerate calendar life degradation.

Operating Temperatures
All battery types have specific temperature ranges of operation and Li is no different.  Typically, lithium batteries can be discharged safely down to -4F (-20C) and up to 120F (49C) to 140F (60C) depending upon the manufacturer's spec.  Charging of lithium ion batteries is only permissible at temperatures above 32F (0C) unless the battery has an internal heater and temperature sensor which will allow charging below an ambient temperature of 32F but not below an internal temperature of 32F.   Charging a Li ion battery bellow 32F will cause damage to the internal cells by causing some of the Li ions to plate as Li metal on the anode surface rather than intercalating between the carbon planes in the graphite anode.  This happens because there is not enough thermal energy to drive the Li ions into the graphite structure.  This reduces the capacity of the battery and if done too often can lead to the formation of Li metal dendrites which short across the separator to the cathode causing catastrophic failure of the battery.   Li ion batteries also have a maximum temperature at which they can be charged which ranges from 113F (45C) to 131F (55C) depending upon the manufacturer's spec.  The battery itself produces heat during discharge which combined with a high ambient temperature can cause swelling of the cell and venting.  A battery with an internal temperature sensor connected to the BMS will prevent charging and discharging out of the battery's specified temperature range.

It is also possible to damage a Li ion battery by trying to charge it too fast with too high of a current.  Manufacturer's spec the charging current between 0.2 and 0.5C meaning, 20A or 50A for a 100Ah battery (10 to 25A for a 50Ah battery, etc.).  Once again the reason has to do with the mobility of the Li ions.  If they arrive at the anode too quickly, i.e. at too high a charging current, they can begin to pile up at the surface of the anode instead of diffusing into the graphite lattice.  Check the manufacturer's specification for temperatures of operation and charging and discharging maximum currents.

Another common misconception about Li ion batteries is that they perform poorly at cold temperatures.  The fact is that all battery chemistries including lead acid have less capacity at temperatures below freezing.  This is simply the result of the fact that batteries work by the process of diffusion from one electrode to the other.  Diffusion rates are a function of temperature with rates decreasing significantly at low temperatures.  However, as indicated above, Li ion batteries retain more of their capacity at low temperatures than lead acid batteries, hence they actually perform better at low temperatures with the caveat that they cannot be charged below freezing.

Charging & Storing a Li Battery
Many people make the mistake of trying to use a lead acid battery charger to re-charge a Li battery.  The problem with this is that a lead acid battery charger will stop charging a Li battery before it reaches the required 14.4 to 14.8V required to fully charge the cells inside.  This results in charging the battery to only 70 - 80% of its capacity.  Not only that, but the typical BMS will not perform the important function of cell balancing until the top end voltage is reached.  Over time, this will degrade the overall capacity of the battery even if you later use a charger capable of charging to 14.4V.

Another source of confusion when charging a Li battery can result when the battery is fully discharged (SOC at 0%) to the point that the BMS shuts down the output.  If you put a volt meter on the battery after the BMS has shut it down you will measure a voltage of 0V.  Many battery chargers, including some with a Li battery setting, will not charge the battery if they see 0V.  Make sure that the charger is one which specifies 0V charging like this one from Li Time or similar.  A trick to get a non 0V charger to work (still needs to have a Li setting) is to connect any 12V battery or jump starter to the Li battery momentarily to "wake up" the BMS.  It only takes a momentary contact making sure to connect the positives to each other and the negatives to each other just like jump starting a car battery.

It is always important to keep a Li ion battery from getting too hot and for we astronomers that means keeping out of direct sunlight on the viewing field.  This is especially true when charging the battery as internal heat is produced when charging (also when discharging) a Li battery due to its internal resistance.  The added thermal burden of high ambient temperatures and direct sunlight can raise the internal battery temperature and result in cell damage.  I always tuck my battery or power station in the shield behind my solar panels to keep it cooler.

If a Li battery needs to be stored for an extended period most manufacturer's suggest storing it at a 50% SOC although at least one company, Battleborn, says to store it at a 100% SOC.  Based upon the fact that published literature show that a high SOC is more stressful to a Li battery it is probably best to follow the lower SOC suggestion of 50%.  Because Li batteries have a low self-discharge rate of 2-3% per month they only need to be recharged every 3 - 6 months.  To make sure that the BMS balances the internal cells you would need to recharge it to 100% SOC and then discharge it to the whatever SOC you plan to store it at, say 50%.

Li Battery Safety
While lead acid batteries can cause fires and explode if not properly handled, lithium batteries have received a lot more media attention for dramatic failures in recent years.  The term "venting with flame" was coined to describe thermal runaway events where the can containing the cell components breaks and fire escapes.  Despite all the media attention, lithium batteries are quite safe when handled and operated properly.  The Occupational Health and Safety Administration points out that lithium batteries are "generally safe and unlikely to fail, but only so long are there are no defects and the batteries are operated safely."

Lithium batteries fail for one of several reasons.  Manufacturing defects like the presence of tiny metal particles in Sony batteries in the 90s can cause an internal short and resulting failure.  Manufacturing processes have improved greatly since then, but it is probably a good idea to purchase a lithium battery from a supplier who has been around for a while and has a good reputation as one would expect them to source high quality components and use proper assembly and testing procedures.

Like lead acid batteries, lithium batteries can fail when damaged from falls, punctures or excessive vibrations.  They can also fail from improper use such as charging below the low temperature cut-off, charging with too high of a current, a short circuit or excessive temperatures.  The internal BMS is a major safety feature to help insure safe operation.  But it can only prevent operation outside the specified temperature limits if it has one or more internal temperature sensors which not all lithium batteries have.  In summary, if handled and operated properly a quality lithium battery should not be any more dangerous than a lead acid battery.

Many of the Li ion battery failures are from devices like cells phones, tablets and laptops which use LiCoO2 as the cathode material because it has one of the highest energy densities.  However, it also has the lowest thermal runaway temperature as well.  One should not draw generalized conclusions about the safety of LiFePO4 and LiNiMnCoO2 batteries and power stations from failures in devices using LiCoO2.

Lithium vs Lead Acid Battery Cost Comparison
Another popular misconception is that Li ion batteries cost more, even much more, than lead acid batteries.  The fact is the total cost of a lithium battery is much less the cost of an AGM battery.  A check on Amazon shows  100Ah AGM deep cycle batteries selling for $165 to $204 while name brand LiFePO4 batteries from Chins and Li Time sell for $320 and $350, respectively.  Knowing that lead acid batteries should not be discharged more than 60% while LiFePO4 batteries can be safely discharged 100% one would need 1.7 100Ah AGM batteries to supply the equivalent energy as a single LiFePO4 battery.  So the actual up front cost comparison is $3.20  to $3.50 per Ah for LiFePO4 versus $2.75 to $3.40per Ah for AGM.  Now we must take into account the useable life of each battery type.  For LiFePO4 the most conservative estimate is 2,000 full discharge cycles while the most optimistic estimate for an AGM is 750 cycles.  Taking this into account the total cost per Ah over the full cycle life is less than 0.2 cents for LiFePO4 and 0.4 cents for an AGM battery.  So a LiFePO4 battery costs less than half that of an AGM battery over the full expected cycle life of the battery.

Another way to look at this is the calendar life of the battery.  As we mentioned above, the calendar life of a LiFePO4 battery is 10 years while that of an AGM battery is ~5 years, nearly half as long.  So, no matter how you compare the two, a LiFePO4 battery is a better value than a lead acid AGM battery these days.
​
Now the cost comparison is different when we talk about Li power stations like those from Jackery and EBL.  The EBL 1000Wh power station sells for $490, is expected to provide 500 full discharge cycles and provides 83Ah per cycle.  The total cost comes to 1.2 cents per Ah.  Power stations are more expensive options compared to stand alone LiFePO4 batteries because they provide many more features besides dc power including pure sine wave inverted AC power, multiple USB power ports, an internal solar charge controller, internal meter and display, etc.

Summary and Conclusions
As we have seen, Li ion batteries have many advantages over lead acid batteries which is why they are fast becoming the batteries of choice for amateur astronomers.  A 100Ah LiFePO4 battery with a capacity of 1280Wh can be expected to provide power to an astrophotography or Electronically Assisted Astronomy setup requiring 64W of power (5Ah) for a total of ~20hrs before needing to be recharged.  They are in fact cheaper than lead acid and perform better than lead acid at all temperatures.  When handled and operated correctly Li ion batteries are safe.  To achieve the maximum useable life and capacity, as well as, prevent damage to the battery or even a catastrophic failure, always follow the manufacturer's recommended specifications and operating instructions.

Links are affiliate links which help to support this web site at no cost to you.  If you purchase a lithium battery or portable power station as a result of reading this Blog I ask that you please use my links for your purchase.

Get 3% Off any LiFePO4 battery from Li Time using coupon code CURTISM and the Li Time link below

LiFePO4 Batteries
Li Time (formerly Ampere Time)
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Portable Power Stations
Jackery  
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    Jackery's Web Site   www.jackery.com?aff=196
EBL   amzn.to/3nyNc8i
Bluetti    amzn.to/40vemvb

Genuine RiG Runners

Last February I reviewed my Pegasus Power Box Advanced (PPBA) power distribution and USB hub which I have been using for more than two years  www.californiaskys.com/blog/archives/02-2022.  While I like the PPBA and will continue using it, there are cheaper and simpler options available for those who only want a simple device.  I am speaking of the RigRunner which is widely used in the Ham Radio hobby as a power hub.  The RigRunner is made right here in the USA by West Mountain Radio in Waukesha, WI.  www.westmountainradio.com/rigrunner.php.  They make 10 different power distribution hub models with prices ranging from $75 to $180 which is much less than the cost of the cheapest Pegasus Power Box.  

While the PPBA has a lot of features including the ability to turn power ports On/Off, an environmental sensor which can automatically turn on and adjust the power level of my dew heater, an internal meter which records voltage, current and power and a software application which allows one to see all of this and control it from a computer, I seldom use any of these features on mine.  If you are like me and, if you already have or do not need a USB hub, one of the RigRunner power hubs may be a better choice for you.

igRunners are made of 0.062 gauge aluminum case with a powder coating paint and silk screened labels. A simple circuit board made with 3oz copper, double sided plated through holes and a solder mask over bare copper wire is inside.  Models are available with 4, 5, 6, 7, 8, 10 and 12 outlets to power a variety of devices.  Each output comes individually fused.  The user has the option to easily change the fuse value since simple ATC/ATO automotive fuses are used and fuses are accessible from the front panel.  The DC input is also fused and is user adjustable.  Genuine Anderson Power Pole connectors are used for both the power input and outputs.  Power Poles allow for secure connections and prevent connecting a device with reversed polarity.  Models are available with the outputs configured horizontal to the base of the RigRunner or vertical to meet different user installations.  All models are 1.4" in height by 3.0" in depth while the length varies from 4.7" for the 4 outlet model up to 11.75" for the 12 outlet models.

Models are rated at 40A total current, except the 8012 model which is rated at 80A.  Any output can provide up to the maximum current as well, but the total cannot exceed 40A, or 80A for model 8012.

In addition to different numbers of outputs, 3 models include 1 or 2 USB charging ports with a maximum of 2A per port.  The 4007U model includes several additional features such as:

• A solid state On/Off button
• A 3 x 7 segment display showing the supply voltage and load current
• Automatic shutoff with an audible alarm in case of high or low voltage
• A 2A USB charging port
• Remote wired On/Off and lock out capability

Other Power Distribution Hubs

Powerwerx sells 4 position and an 8 position simple power distribution hubs where any one position is used for the input.  These are made of sturdy ABS plastic with a sealed internal copper bus bar and are rated to 45A total current for all positions total or any single position.  They are also made in the USA and also use genuine Anderson Power Pole connectors.  The 4 position hub sells for $37 while the 8 position sells for $50.  Both hubs are 1.3" high by 0.97" deep.  The 4 position model is 2.33" wide while the 8 position model is 3.75" wide.

There are a number of Chinese companies that sell power hubs which appear to be clones of the RigRunner.  Examples are the HCDC 8 output model which sells for $72 and the Chunzehui 8 output model for $75.  Designs and features appear to be near clones of the RigRunners but they do not use genuine Anderson Power Poles.  Instead they use Power Poles which are also Chinese clones of the original.  That being said, these appear to be well made and have mostly good reviews.

Summary
In summary, if you do not need a combined power and USB hub, and just want simplicity of design and use, something like the RigRunner should be a good option for you.

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After posting reviews of the Jackery 1000 and the Bluetti AC50S power stations I thought I was done with the world of all-in-one power solutions for the field.  But, this past summer I was contacted by EBL and asked if I would be willing to review one of their portable power stations, the Voyager 1000.  I must admit that I had never heard of EBL so I did some homework and found that they have been around since the 90's as a supplier of all kinds of batteries (AA, AAA, C, D, 9V, alkaline, Ni-Cd, Li, etc.) as well as battery chargers.  Apparently they decided to participate in the recent trend in the market and have come out with four different capacity portable power stations of their own that I think are worth considering.  In addition to the 1000Wh model that I tested they also have a 500Wh model ($470), a 500Wh model ($419), a 300Wh model ($179) and two newly introduced larger capacity models using LiFePO4 cells, the 1843Wh model ($899) and the 2097Wh model ($999).  These are some of the lowest cost portable power stations from a well known battery manufacturer.  EBL also has 100W and 200W solar panels to charge the power stations away from home.  A quick check over the specs and features of their Voyager power station had me intrigued, but the phenomenal price, ($470) is what made me decide to accept their offer and conduct my own review.  More on that later.

I received their Voyager 1000 power station along with two 100W solar panels near the end of July.  I followed the same procedure as I have for all my other reviews of batteries and power stations which is to first conduct bench tests to verify the capacity and re-charge times followed by several months of testing in my home observatory and finishing with a field test at a star party.  So let's begin.

Basic Features of the EBL Voyager 1000
The first thing I noticed is the solid construction of the power station.  The Voyager is made of ABS plastic and has rubber bumpers on all four corners to protect it from damage from the inevitable occasional collision with an obstruction when loading and unloading for travel.  For additional cushioning It also has four rubber feet on its bottom along with the complete list of product specs.  With dimensions of 15.67" x 10.31" x 10.79" and a convenient sturdy handle the Voyager packs a lot of energy at 1000Wh into a small and highly portable package.  I very much like the fact that the handle folds down flat unlike another major supplier of power stations so that you can stack other things on top when packing for a trip.  All of the controls and ports are located on the front of the Voyager for ease of use.  At just 18.7lbs the Voyager is almost 7lbs lighter than its competitor, the Jackery 1000.

The Voyager 1000 is rated to supply 999Wh of power in any combination of DC, AC and USB power.  As is common with portable power stations, it has a standard cigarette lighter socket for DC connections, but it also has two 5.5mm x 2.1mm DC ports as well.  All are rated at 8A each (8A max all three combined) and 12V.  The 5.5mm x 2.1mm ports are very convenient for us amateur astronomers since this is the industry standard electrical connection on most astronomy equipment.  I had no trouble with my cigarette plug coming loose from the cigarette lighter socket during months of testing, but it is nice to have the option of the other DC power ports.  For AC power a pure sine wave inverter capable of 1000W steady state (2000W Max) is built in with two AC ports.  This is convenient if one needs to use AC power for their laptop or prefers to power their mount with an AC adapter.  My wife used this to power her laptop on a recent boondocking trip in our RV. There are plenty of USB ports to re-charge phones, tablets and even laptops.  The Voyager has 3X 3.0 Quick Charge USB A ports capable of 18W of power and a Power Delivery (PD) port with 60W of output.  I used these to recharge my phone during my 4 days of field testing.  And, there is a 10W wireless charger on the top of the power station.

As is typical the EBL power station has an MPPT solar charge controller built in to accept power from one or more solar panels.  I like the fact that this one has both an 8mm input and a Power Pole input to provide extra capability for different connectors you might find on solar panels and AC chargers.  The Voyager comes with a 150W AC charger and a car adapter cable to charge the unit from the car's cigarette power port.  The maximum charging power input is 150W so that two 100W solar panels is probably the maximum you would want to use since any power beyond 150W will not be used by the Voyager.  Pass through charging is a nice feature common to most power stations which means that you can use any of the power ports while the unit is being recharged either with solar or the AC power adapter.

You will find a master power button and individual power buttons each for DC, AC and USB power on the front of the unit.  There is also a small LCD display which shows the percentage state of charge (SOC) in increments of 1%, along with the instantaneous power being consumed and/or the power being charged.  This is helpful to keep track of the time remaining to power your devices.  The Voyager also has a flashlight feature on its front which provides a nice bright light as needed, which is not typically something we use at star parties but will be helpful on camping trips.

Like all Li power solutions the Voyager has an internal BMS which protects the internal cells from being over discharged, over charged or shorted.  The BMS will shut the output down when 100% of the useable capacity has been depleted.   EBL uses LiNiMnCoO2 (NMC) cells just like most of the other portable power stations because of its high power to weight ratio.  EBL warrants their Voyager for 12 months and, although they do not specify the number of full discharge cycles to expect, this is typically 500 for NMC.  Operating temperatures are similar to other power stations with a discharge temperature range of 14 to 113 deg F (-10 to 45 deg C) and a re-charge temperature range of 32 to 104 deg F (0 to 40 deg C).

Bench Test Results
As with my other power supply reviews the very first test is a bench level test to check the actual capacity versus the manufacturer's spec.  Usually these are quite close with the actual power available being within 90% of the spec. with the internal BMS accounting for some of the difference between spec and actual power measured.  After charging the Voyager to 100% SOC  I attached the DC output to a load tester and set the discharge current to the maximum of 8A.  Typical for an NMC power station, the output voltage is regulated.  With no load the output voltage was 12.9V.  With an 8A load (or a 5A load) the output voltage was maintained at 12.4V for the duration of the test.  I repeated this test 3X to check for consistency and found that the average capacity was 912Wh (909, 921, 920, 898) or 73.3Ah (72.9, 73.8, 73.9, 72.7 ).  As you can see the repeatability is excellent and the overall capacity is ~92% of the manufacturer's spec which is typical of these solar power stations.  For comparison I measured a total capacity of 908Wh for my Jackery 1000 power station.

During the discharge test I periodically measure the output voltage to confirm the quality of the voltage regulation and to see at which point the output drops below 12V.  You can see from the plot that the voltage is well regulated at 12.45 +/-0.1V all the way until the BMS cut off the output.

One thing that I noticed while discharging the Voyager 1000 was that the SOC meter on the unit appeared to read high.  Since I recorded the Voyager's SOC meter reading and the Wh and Ah during the discharge tests I could compare the SOC reading to the actual SOC knowing the actual capacity (916.7Wh) determined from the three full discharge tests.  What I found is that the SOC meter tracks to the manufacturer's specification of 999Wh within 5% or less.  However, since the actual capacity was 917Wh, the meter is reading ~10% higher than the actual remaining power between meter readings of 60% and 10% SOC.  For comparison, the SOC reading on my Jackery 1000 was within 3% of the actual SOC all the way to cutoff.

Another bench level test is to verify the maximum current that each of the DC output ports can support.  In this case the manufacturer specs 8A max but I was able to push the output to 10A without any apparent issues.  I do not suggest that you run your Voyager above the spec of 8A as I only do this test to ensure it will work at 8A without any problem.

​Once fully discharged the next bench test was to re-charge the unit with the included AC adapter.  Like the discharge test, this one was conducted 3X and the result was a very repeatable 7.7hrs (7.7, 7.7, 7.55)  to go from 0% SOC to 100% SOC.  One interesting thing to note during the re-charge cycle is the fact that the SOC meter on the front panel indicated 99% SOC at 6.5hrs but it still took 1.2 hours more to reach 100% SOC.  This was very repeatable as well.  Curious to know whether this was real, I charged the Voyager until the meter just reached 99% and then did a full discharge test.  This time, my load tester measured a total of 743Wh which is just 81% of the measured capacity.  This means that when the SOC meter just reaches 99% of capacity it still has another 173Wh to go before it is fully charged.  The numbers all add up since at ~1.2hrs  at 150W will pump an additional 180Wh of energy  into the power station to reach a full charge.  The moral of the story is, when charging let the BMS shut down the charging input to be certain a full charge is achieved.

While for astronomy applications in the field it is always better to use DC power directly rather than to use an AC inverter sometimes we just need AC power.  So, I measured the efficiency of the Voyager's AC inverter by using it to power a fan through a full discharge cycle.  I measured the AC power output using a KilaWatt meter.  After adjusting for the slight power consumption in the meter itself I found that this inverter is ~93% efficient in converting DC to AC which is excellent.

Solar Recharging
When we are out in the field we do not usually have AC power available and have to rely on solar panels to recharge our power supply.  As I mentioned in the introduction, EBL also supplied 2 of their 100W Apollo solar panels which I used to recharge the Voyager.  The dual charging inputs (8mm & Power Pole) makes it easy to use solar panels from any number of other vendors if you want.  With full sun in late summer I was able to fully recharge the Voyager in 9.5hrs which is longer than the 7hrs indicated on the EBL website.  This would indicate that I was not getting the full 150W of charging input power that I was getting from the AC charger.  Unlike AC charging, solar charging depends upon the amount of sunshine, angle of the sun relative to the panel and the temperature of the panel so one can expect a wide range of recharge times under different conditions and times of the year.  I fully expect that this time would come down if I had run the test during the summer when the sun was higher in the sky.

Backyard Observatory Testing
Before taking the Voyager into the field I used it over a period of 3 months to power my equipment in my home observatory.  This provides an opportunity to get used to its controls and operation and to find out if there are any glitches or incompatibility issues with my equipment.  At home I have a Celestron C11 Edge  mounted on a Software Bisque MX mount.  I use a DC-DC voltage converter to boost the voltage from 12V to the 48V that the MX requires.  For astro-imaging I use a ZWO ASI1600MC uncooled camera and a ZWO ASI224MC camera for guiding.  When needed I use a dew strap to keep dew from forming on the corrector plate.  I use a Celestron motorized focuser and a pair of fans from Deep Space products to help cool down the optical tube in the early evening.  A  Beelink Mini-PC runs all of the astronomy software to control all of the equipment and imaging runs.  I can connect to the Beelink wirelessly via a GL.iNET wireless router with a separate laptop from which I can control everything and keep track of progress.  Power is distributed to all of the equipment at the scope, but not the laptop, through a Pegasus Power Box Advanced power and USB hub.  Power is supplied to the Pegasus from the Voyager using its cigarette port.  Total power consumption varies from ~30 to ~50W.  I had no issues running this way for the 3 month duration of the testing.

Field Testing
The field test is my favorite part of the review which is where I get to take the unit out to a dark site during a star party to see how it performs in real world conditions.  In this case I took the EBL Voyager with me to the Nightfall star party in Borrego Springs, CA.  The Voyager supplied all of the power for my setup which consisted of the same equipment as at home, except that my Celestron C11 was mounted on a Software Bisque MyT mount instead of the MX.  Because of the desert climate I had no need for the dew heater.  In total, my power load, excluding the laptop which was powered separately, was ~38W.  Over 3 nights I powered all of this without recharging the Voyager for a total of 20.6hrs with enough power remaining that I could have powered this setup for a total of ~24hrs before needing to recharge.

Now, everyone has a different setup so how long can you expect the EBL to power your particular rig?  I have put together a chart which breaks down typical setups and an estimate of the accompanying power consumptions into three groups.  A low power setup would consume 30W or less and would include pretty much any scope and mount combination along with a Raspberry Pi, Mini-PC or Intel Nuc to run all of the software and hardware.  It would also include an uncooled camera along with a guide camera, a motorized focuser, cooling fans and maybe even a filter wheel.  It might also include a power distribution hub, powered USB hub or combination like my Pegasus Power Box.  With a setup like this one could expect the Voyager to supply enough energy to run for at least ~30hrs.  That could be enough for 2 or even 3 full nights without the need to recharge the Voyager.

For those who use a cooled camera and possibly a dew heater, the power consumption can rise to as much as 60W.  In this case, the total run time would be cut in half but still allow for a full night or 2 short nights of imaging.  For those who run their equipment with a 15.4" laptop instead of a lower power consuming mini-pc, etc., the power required jumps to between 90 and 120W depending upon the particular laptop model, how long the monitor is kept on and what other power conservation approaches are taken.  In the extreme case of 120W, one might expect to have enough energy to run for ~7hrs before needing to re-charge.

EBL Voyager 1000 Summary 
Overall I was very happy with the performance of the Voyager 1000 during my 3.5 months of testing.  The Voyager performed as expected providing consistent steady power for all of my equipment right down to BMS shutoff at 0% SOC.  For $499.99 including a $380 coupon on Amazon the Voyager is nearly half the cost per watt-hour as many of the other power solutions on the market.  That's just $0.50 per Wh of energy.  Between its performance and cost this all-in-one power station should provide stiff competition in this market. I will reiterate that from the outside the Voyager is well designed and well put together.  I will leave it to other reviewers to do a tear down review so that we can see if it is equally well made on the inside.  

What I like:
1.  Price.  With the current coupon on Amazon the Voyager 1000 sells for $499.99.  That's $0.50 per Watt-hour compared to $0.95 per Watt-hour for the Jackery 1000. 
2. Two 5.5mm x 2.1mm DC power ports consistent with the standard power ports on most astronomy equipment.
3. Compact, light weight design with rubberized bumpers on all four corners.
4. Sturdy folding handle which allows for better stacking for a trip.
5. QC 18W USB power ports for faster charging.
6. All ports and controls on the front for easy access.
7. MC4 to 8mm charging cable included.

What I dislike:
​1. 1 year warranty compared to 2 years for its competitors.
2. DC output is limited to 8A compared to 10A for its competitors.  However, for typical astronomy applications, 8A or ~100W is more than sufficient.
3.  EBL should specify the number of full discharge cycles expected.
4.  EBL needs to fix the SOC meter so that it more accurately reflects the SOC both during discharge and charge cycles.

Mini-pcs are becoming increasingly popular for both Electronically Assisted Astronomy (EAA) and astrophotography.  This is because a mini-pc allows one to connect remotely to the telescope, mount, camera, and other equipment with a laptop, tablet or phone without  being tethered by a USB cable.   Remote may mean inside one's house while the telescope is out in the back yard or inside a small tent or EzUp where you can stay comfortably warm and away from annoying bugs when observing away from home.   It may even mean sitting in your own house with your telescope set up at a distant remote observatory.  In my case, it means being inside my house when observing at home with my equipment setup in the backyard observatory or inside my RV when at a star party or other remote site.  Being untethered allows me to move freely from inside (house or RV) to the side of the telescope whenever I need to be close but then being able to return to the inside for most of the night.

Utilizing a mini-pc at the telescope will also reduce the power required to keep everything running through the night.  A mini-pc uses much less power than a typical laptop.   If you connect remotely to the mini-pc with a laptop you can still save power since you do not have to have the laptop on all the time since it is only being used as a monitor to check in on the mini-pc from time to time.  In fact, you can simply turn off the laptop once the mini-pc is up and running and leave it off until you are ready to shut down the session.  A tablet or phone can be used instead of the laptop to remote into the mini-pc which gives more options in terms of saving power since these use much less power than a laptop.

What is a Mini-PC?
A mini-pc is a headless computer which comes in a small form factor typically 5" - 6" on a side by about 2" - 3" thick or even smaller.  Headless means that it comes without a monitor, keyboard or mouse.  This cuts down on the size, cost and power consumption, all important for astronomy applications.  Since a mini-pc is a computer it will have a CPU, RAM, non-volatile memory, a GPU, USB and HDMI ports, a LAN port, WiFi, and Bluetooth capability.  It will also come with an installed operating system such as Windows 10 or 11.  The mini-pc can do anything a laptop can while running the applications needed for complete control of mounts, cameras, focusers, dew heaters, etc.  This includes running image capture software, guiding software, planetary software, plate solvers, planning software and imaging session automation and control software like NINA or SGP.  For instance, on my mini-pc I have The Sky X for mount/camera/focuser control and image capture, Sharpcap for EAA, Ph.D2 for guiding, All Sky Plate Solver and ASTAP for plate solving, Cartes du Ciel as my planetary software, and Sky Tools 3 Pro for planning.  I recently added NINA which will take responsibility for overall control and sequencing of my astro-imaging sessions which still uses TSX, Ph.D and ASTAP.

In general, a mini-pc is not expected to do the heavy lifting of post processing the photos captured during an astrophotography session, although it is expected to handle the live image stacking, dark frame subtraction and stretching typical in an EAA session.   Usually, the burden of post processing astro images is tasked to a separate, more powerful and more expensive laptop or desktop computer.  But, there is no reason it cannot be done on the mini-pc if configured to do so which requires a keyboard, mouse and monitor.  Even when post processing is left to a separate computer, it is imperative to have a keyboard, mouse and monitor to attach to the mini-pc for initial setup and for analysis in case something goes wrong.  In two years I have only had to pull out these once in the field and it turned out that the problem was operator error, not something wrong with the mini-pc or my WiFi router.  Still, having these as backup is essential in the rare case that something goes wrong.

​​Choosing a Mini-PC
When it comes to mini-pcs there are a seemingly endless number of options available which constantly change as new hardware components become available.  New mini-PCs can be found for under ​​​$200 on models with Celeron and Core i3 processers to over $1000 for models with high end processers, GPUs and lots of memory.  Keep in mind that even with the same models, prices fluctuate frequently both up and down.  The correct choice depends upon one's particular application, future plans and pocketbook.   

Typically, the trade off in performance  and price leads to mini-pcs used for astronomy costing somewhere between $200 to $500.  Beelink is probably one of the most popular mini-pc manufacturers in this price range.  Recently, inexpensive models from Mele Quieter have gotten a lot of notice on the Cloudy Nights forum as well.  Intel NUCs (Next Unit of Computing), designed and built by Intel, are also quite popular and include some of the high end mini-pcs as these   NUCs come in many configurations including kits which can be customized to the users requirements.  

When choosing a mini-pc the first feature to consider is the CPU.  At this point in time mini-pcs used for astronomy usually include a Celeron or Core i3 processer for the less expensive models or an i5 processer for the slightly more expensive models.  Many people report success in astrophotography and even EAA with mini-pcs using Celeron processors.  However, for high data rate applications as is the case with larger format cameras (20Mpixels or larger) or live stacking of very short exposures (less than 5 sec subs) with dark frame subtraction and flat frame calibration for EAA, the Celeron class of processor may not be up to the more challenging tasks.  In these situations an i5 processor would be a safer choice while the added cost of an i7 processer might be better applied to more RAM or a larger and faster SSD.  For planetary imaging requiring extremely high image capture rates one should consider at least an i5 and possibly an i7 processor with fast SSD storage.

​Celeron processors found in these mini-pcs include the Gemini Lake J4125 and the Jasper Lake N5095.  For Core i5 processers the Tiger Lake 113567 and Coffee Lake 8279U are typical.  In addition to processing speed and cost another attribute of CPUs to be considered is the Thermal Design Power (TDP) which is indicative of the maximum power that the CPU can generate.  The higher the TDP the more power one needs in the field to keep the mini-pc running all night long.  One of the desirable features of the mini-pc is its lower total power consumption compared to a laptop.  The accompanying table shows the tradeoff in CPU capability and TDP.

After the CPU the amount and type of RAM and mass storage is probably the next most important consideration.  8GB of RAM is sufficient for most situations and is fairly common in pre-configured mini-pcs, while 16GB can help when many applications are open at the same time.  As far as mass storage one should consider 128GB to be the minimum choice in which case you may have to constantly download image files to another storage device after an imaging session.  I opted for 256GB which allows much more margin, but even then I sometimes wish that I had paid the extra for 512GB.  The choice will depend on your imaging/EAA habit and how often you are willing to transfer images from your mini-pc to your processing pc. 

Mass storage on the mini-pcs often used for astronomy typically have one of three types of mass storage including M.2 SATA SSDs, M.2 NVE SSDs or eMMC.   The first two can be replaced while eMMC is soldered onto the motherboard and cannot be replaced.  NVE SSDs use the PCIe interface which is much faster than the SATA interface used by SATA or eMMC devices.    All will work but the M.2 NVE SSD is the better choice for high data rate applications.

Probably the next most important consideration in choosing a mini-pc is the number and type of USB ports because of the need to connect our many astro devices to the mini-pc.  Most mini-pcs in the price range being discussed usually provide  at least 4 USB ports in some combination of USB2.0 and USB3.0.  Some also provide a USB Type C port with even faster data transfer rates.  Don't forget to reserve one USB port for a WiFi dongle when using a wireless keypad and mouse.  On  other hand, if like me, you have a USB hub like the Pegasus Power Box which you use to connect your astro devices, you will only need to connect the hub to the mini-pc, preferably over a USB 3.2 port for fastest transfer rates.

Another choice is whether or not to choose a mini-pc with a fan or not.  Fans consume additional power.  And they can, in principle, cause vibrations although I have never witnessed any such problem with my mini-pc attached to the leg of my tripod.  On the other hand, fans will keep the CPU cool so that it can operate at its highest speed whereas air cooled mini-pcs can get hot causing the CPU to throttle back.  Beelink tends to incorporate fans into their models while MeLE Quieter does not.

Many folks agonize unnecessarily over the fact that some mini-pcs require 19V power input instead of 12V.  This is easily rectified with an inexpensive DC-DC boost converter which takes a 12V input and provides a steady state 19V output.  The boost converters are ~95% efficient while the AC transformer typically supplied with any mini-pc is likely ~80% efficient.  I find the easiest way to incorporate these into my setup is to attach Anderson Power Poles to the leads and use Anderson Power Pole to 5.5 x 2.1mm adapter cables to connect to my equipment.

All mini-pcs include an ethernet port for wired connection, WiFi and BT capability, along with one or more HDMI ports.  You will need one HDMI port to connect a monitor initially to set up the mini-pc and any time something goes wrong with your connection to the mini-pc and you need to trouble shoot the situation.  Mini-pcs come with Window 10 or Windows 11 software already installed.  Look for the Pro version which is required for some remote connection software like Team Viewer and Remote Desktop.

Mini-PC Models to Consider
Below are a number of different mini-pc models currently available.  Prices will vary and over time models will change, but this can be a good starting point.

Beelink has a large following in the astronomy community judging from posts on CN and is the brand I have used and been happy with for the past 2 years.  You can search through all their models on the Beelink Amazon store.  A few examples are worth considering.

The Beelink U59 Pro comes with a Celeron N5105 processor, 8GB of RAM, a 500GB M.2 SATA SSD, 4 x USB 3.0 and 1 x USB C ports, 2 LAN ports, 2 x HDMI ports, WiFi, BT, and Windows 11 Pro.  It has a cooling fan and operates on 12V and is currently on sale for $219.  You can add 8GB more RAM for another $25.

The Beelink SEi8 has an i5-8279U processor, 16GB of RAM, a 500GB M.2 NVME SSD, 4 x USB 3.0 and 1 x USB C ports, 1 LAN port,  2 x HDMI ports, WiFi, BT and Windows 11 Pro.  It also has a cooling fan and operates on 19V and also has an auto startup feature so that you can set it to automatically turn on at a set time each day.  This model is currently on sale for $397.  Compared to the model above you get a faster processor, twice the RAM and a faster SSD.

If you are looking for a fanless mini-pcs, the models from MeLE Quieter are becoming popular among amateur astronomers lately.  Here are two worth considering.

The MeLE Quieter 2Q uses the Celeron J4125 processor, 8GB of RAM, 128GB of eMMC storage, a Micro SD card slot of storage expansion, 4 x USB 3.0 ports, 1 LAN port,  2 x HDMI ports, WiFi, BT and Windows 11 Pro.  It does not have a cooling fan and can also be configured for auto startup.  This model is currently on sale now for $210.  Like most mini-pcs there are upgraded versions of this model with up to 512GB of eMMC storage for an additional $90.

The MeLE PCG35 has a Celeron N5105 CPU, 8GB of RAM, a 256GB NVMe M.2 SSD, a Micro SD card slot of storage expansion, 2 x USB 2.0 and 2 x USB 3.0 ports, 1 LAN port,  2 x HDMI ports, WiFi, BT and Windows 11 Pro.  It does not have a cooling fan and can also be configured for auto startup.  This model is currently available for $310. 
​
Both of these MeLE models require 12V input power.

Intel NUCs can be found at the Intel Store for as little as $200 to well over $1000.  An example is the Intel NUC 10i3FNHN which currently lists for $499 and includes an i3-10110U processor, 8GB of RAM, an 512GB of PCIe SSD, 3 x USB 3.2 ports, 1 Thunderbolt (Type C) port, 1 HDMI port, 1 LAN port, BT, WiFi, an SD card slot and Windows 10Pro.  It requires 19V for power.

Mini-PC Operation
Being small and light, a mini-pc can be mounted on top of the telescope which minimizes the length of cable runs between cameras, focusers, dew heaters, filter wheels, the mount and the pc.  Often the mini-pc can be found mounted to the leg of the tripod or at the base of the mount.  If the mini-pc has a cooling fan, this may be the best place to mount it to minimize the chance of vibrations in the optical system.  This is my typical configuration since I have a Software Bisque Mount with through the mount cabling.

In addition to the mini-pc some method to connect between a laptop/tablet/phone and the mini-pc is required.  This involves a remote desktop application like Team Viewer, VNC Connect, Remote Desktop or one of the many others which are free and easy to use.  These generally require that the mini-pc has the Pro version of Windows to work.

The second requirement for remote connection is the ability to make a WiFi connection.  At home this could simply be your home internet network assuming that you have a LAN line to connect to the mini-pc in the back yard.  I use a Cat5 cable I strung out to my backyard observatory 10 years ago to connect from my laptop anywhere inside the house to my mini-pc outside on my home network.  In the field or at home if you don't have a wired connection in the back yard, you will need to create your own WiFi network.   This is simple to do with an inexpensive portable router.  I have reviewed 2 such inexpensive routers from GL.iNet in an earlier blog which you can find here.   A video version of my review can also be found here.  I have been using the GL.iNet 750S Ext (Slate) for 2 years and could not be happier.  I can stay connected from inside my RV to my telescope up to 100 feet away.  At home I can use the Slate as a repeater and connect to my home internet without the need for a LAN cable connection.  GL.iNet has another model capable of higher data rates called the Beryl for just a few dollars more which is worth considering.  If you need help setting one of these up, I created a video showing how to do this step by step.

Summary
Having used my mini-pc for two years both at home and at many star parties I have been extremely happy that I finally made the move to untether myself.  With one exception (operator error) I have not lost any time due to problems connecting or using the mini-pc.  And, I have not noticed any problems when using it for astrophotography or EAA.  Hopefully I have given you a helpful overview of the considerations required to set up your own remote connection so that you can make the right choice for your situation.

The one possible downside of using a mini-pc is that it tends to keep me inside, even at star parties, instead of out under the night sky.  I have had to remind myself that one of the great things about being at a star party is to be able to look up and appreciate the wonder of the Milky Way with my naked eyes.  So, I make it a point to spend some time outside both viewing the night sky and talking with my fellow amateur astronomers instead of spending the entire night away from the action inside the RV.

You can find a complementary video tutorial on this subject on my YouTube channel which you can find here www.youtube.com/watch?v=TRk2wsrOnNM