![]() I have used a wide variety of equipment during my 15 years of Electronically Assisted Astronomy (EAA). This includes refractors, SCTs and even a Newtonian along with all sorts of analog video cameras and CMOS digital cameras. I have also tried many different live stacking software packages including ASI Live, TSX Live Stack and, mostly, Sharpcap. In every case, like so many others doing EAA, I had to pull together all of the necessary components including mount, OTA, camera, laptop and mini-pc, USB and power hubs, cables and SW and integrate all of these to make sure that everything worked seamlessly, which was often not the case. So, I watched with interest over the past 4-5 years as all-in-one Smart Telescopes began to hit the market. With a price point of $499 ($450 on sale) I finally decided to give one a try and purchased the ZWO Seestar S50 Smart Telescope. I have used it extensively in my light polluted back yard over many nights and even tried it out at our club's local dark site to see what it can do. In this Blog I will provide the basic run down of the Seestar's equipment, explain what you need to know to get it working, share some of my images and list what I think are its Pros and Cons. ![]() Seestar's Design The Seestar S50 uses a 50mm f/5, 250mm focal length triplet objective with one element of ED (extra low dispersion) glass. The combination of 3 elements in the objective enables it to focus the red, green and blue light at the same focal plane. Therefore it does not show any hint of chromatic aberration, a purple color fringe around any bright object, which is typical with an objective using only one or two glass elements. In addition, because all three colors focus at the same focal plane the resulting images are sharp with good detail limited by the local seeing conditions. Light from the objective is directed off a pair of mirrors to an internal CMOS camera using the Sony IMX462 color sensor. This sensor has just over 2MPixels arranged in an 1080 x 1920 array of 2.9microns size pixels. As such the overall sensor is is very small with a diameter of just 6.46mm, quite similar the the IMX224 color sensor which first came out around 2014. The small size of the sensor combined with the 250mm focal length of the optics produces a small field of view of 76.5 x 43 arc minutes. While this is large enough to fit the entire image of the sun or moon, it is too small to fit the entirety of large deeps sky objects (DSOs) like the Andromeda galaxy. I normally do not recommend a small sensor like this as it also can make it difficult to find dim DSOs because of the small field of view. However, the Seestar has solved both of these problems for us. First, it has the option to capture images as mosaics up to 2X in width and height of the imaging sensor. With a 2X mosaic the Seestar can now fit the entirety of the Andromeda galaxy and many other large DSOs into one image. Second, the Seestar using Plate Solving to find and locate objects in the night sky. This means that when it goes to a point in the sky where it thinks the object you want is located, it takes an image, calculates the relative positions of the stars in the image, compares the result to a data base, determines accurately where it is actually pointing and commands the mount to move to the right location to center the desired object. So with both of these clever features you are not overly limited by the small size of its imaging sensor. Focusing is accomplished with an internal focus motor which moves the sensor in and out to achieve focus automatically by measuring and minimizing the size of the stars measured in pixels. There is an option to perform focus manually but in my experience the Seestar's automatic focus routine does a very good job of achieving sharp focus. The Seestar has 3 filters and a shutter. The shutter blocks all incoming light so that the Seestar can take dark frames. It automatically creates a master dark frame from 5 individual dark sub-frames which are subtracted from each light frame to minimize the impact of sensor fixed pattern noise such as hot and warm pixels, as well as, sensor dark current. The first filter is an internal UV-IR cut filter which is designed to eliminate star bloat so that images have sharp stars. Seestar automatically deploys this filter on all objects other than emission nebulae. The second internal filter is a Dual Band filter designed to block all light except for that around a 30nm band at the wavelength of OIII and a 20nm band at the wavelength of Ha. This filter will block a large amount of ambient light pollution should be used for emission nebula, not reflection nebula, which have lots of light at these two wavelengths. Th Seestar will automatically place the correct filter in front of the sensor depending upon the object type. The Seestar comes with an external white light filter which must always be placed in front of the lens when there is a chance that sunlight might be directed into the Seestar. If sunlight reaches the imaging sensor without this filter it is highly possible that the sensor will be irreparably damaged. The Seestar is an Alt-Az mount which means that it has two rotation axes, one in the plane of the horizon and one perpendicular in altitude. Alt-Az mounts are commonly used for EAA and do not track the earth's rotation like an Equatorial mount does. While an Alt-Az mount will keep a point object like a star centered in the field of view, stars away from the center and any portion of a deep sky object like a galaxy or nebula not in the center of the field of view will slowly rotate about the center as the earth rotates on its axis. For this reason, the basic rule of thumb is to limit exposures to no more than 30sec to avoid having the stars appear to rotate about the center at longer exposures, looking elongated or trailed instead of point like. For this reason, the Seestar has a maximum exposure of 30sec. The Seestar has an internal computer with 64GB of internal storage which automatically controls all of the hardware and software functions necessary for imaging. It can be accessed through its own WiFi via the Seestar App on your phone or tablet. The Seestar can be connected to a PC with the include Type C USB cable to download images stored in the Seestar's internal memory and recharge the internal battery. However, the Seestar cannot be controlled by a pc. All of the Seestar's function must be accessed through a smart phone or tablet using the Seestar app. The Seestar also has BT which is required for initial setup. The Seestar has an internal 6Ah internal battery which can be re-charged through a USB-C port on the side of the Seestar. You can also connect an external 12V power supply through this USB-C port to power the Seestar longer than the internal battery alone can do. All of these components are sealed inside a 5.5lb (2.5kg) plastic enclosure measuring 5.6" x 5.1" x 10.1" making it a truly light weight and compact Smart Telescope. The Seestar comes with a short but very sturdy tripod with a minimum height of 10.8" and a maximum height of 14.3" which screws onto the bottom of the Seestar with a 3/8" screw. Everything fits neatly inside a sturdy foam carrying case making this truly an all-in-one astronomy solution. As such, the Seestar is by far the most compact and travel friendly of any of the EAA setups I have ever used. It certainly would be very easy to bring as a carry on when traveling by airplane. Initial Setup Connecting to the Seestar for the first time requires a few steps than are needed one time only and the process is well documented in the included instruction sheet. The basic steps include downloading the Seestar App to your phone or tablet, turning on the Seestar's power button (push once, wait, push a second time until you hear the beep) and connecting to it with the Seestar's WiFi. The first time also requires access to the internet but that is not needed for subsequent connections. For all future startups just turn on the Seestar (hold down the power button until you hear the beep), open the App and click on the red Connect button and follow the prompts to complete the connection. When connected you will see the screen below which is the main Seestar App screen, or Home Page, from which you can Open the Seestar arm, enter one of 3 observing modes, view images stored on you phone/tablet or the Seestar's internal drive, view a wealth of video tutorials to get you going, view local weather information and more. You can also see the serial number for you Seestar unit and the current battery state of charge at the top. I encourage you to start by viewing each of the well done tutorials so that you thoroughly understand what how everything works. ![]() Compass & Level Calibration The next step with a new Seestar is to calibrate the internal compass and the level sensor. The Compass Calibration and Level Sensor Calibration procedures will ensure that the Seestar will be able to easily and accurately find and center targets in its field of view. In fact, the Compass Calibration is essential for finding the Sun or the moon during the day as the Seestar will not be able to use its Plate Solve procedure to find either without any visible stars. If you have ever used a Celestron Nexstar or Skywatcher Alt-Az mount you know that the initial setup calls for leveling the optical tube and pointing it north. This is called "Level North" and allows the mount to make a good estimate of the location of objects in the sky using that information along with the local time, latitude and longitude. With this the mount can put the first alignment star close to, if not in, the field of view. Similarly the Seestar compass calibration enables the Seestar to determine the direction for north and the level sensor calibration will allow it to provide feedback to the user when performing the Level Sensor procedure each time the Seestar is set up for an observing session. Hence, Seestar will be able to GoTo the first object and place it in or very near the field of view as well. The difference between the calibration procedures and Level North is that the former only needs to be done once while the later must be done any time the telescope is moved to a new location. To do the calibration and leveling tap the image of the Seestar in the upper left corner of the Home Page to get the next page. Here you have more information about your Seestar along with options to adjust the Sound, the ability to manually adjust the focus, On/Off switches for the dew heater and a Watermark which writes the name of the object imaged along with the exposure time and your location at the bottom of the jpeg images produced after stacking. At the very bottom is a slider to turn off the Seestar power. Just above this is the "Advanced Feature" bar. Tap this to get to the Advanced Feature page where the calibration options can be found. Clicking on the Compass Calibration will display a short video which will guide you through the process. The procedure involves rotating the Seestar about its vertical axis while watching feedback of a white circular ring which slowly turns to green as the calibration is complete. Next, watch the Level Sensor Calibration video which you can find on the App's main page and then then press and perform the level calibration. This involves placing the Seestar on a level surface with a small bubble level on the base of the Seestar, then using thin sheets of paper or similar underneath the edges of the Seestar until the bubble is centered indicating it is level. Once leveled press Calibrate in the App to confirm calibration. This tells the Seestar internal level sensor what true level is so that it can provide feedback to the user when performing the Adjust Level procedure before each session. Again, this sensor calibration procedure only needs to be done once and is not to be confused with the Adjust Level procedure which should be done every time you set up the Seestar. If, at some point while imaging you are having great difficulty getting the Seestar to find and center objects, or it is dropping too many images instead of stacking them you may want to go back and repeat these two calibrations as any degradation in either can impact performance. ![]() On this same page of the App as the Compass and Level Calibration procedures you will find several other important features. At the top you can set the exposure to one of the three possible times. Below that you can tell Seestar to save all of the individual frames as FITS files along with the stacked JPEG image which you may want if you plan to do your own post processing to enhance the final image. The Initialization button takes you to another page where you can turn off the Horizontal Calibration and/or the Auto Focus routine. I suggest you leave these turned on. The Horizontal Calibration routine is on by default and is designed to improve the pointing and guiding accuracy of the Seestar. When the Seestar goes to the first object it will take a short exposure image and perform a Plate Solve operation to use the star positions to get an accurate measurement of the RA and Dec at the center of the current field of view. It will then slew 15 deg in Azimuth to the east and repeat the Plate Solve operation and slew 15 degrees in Azimuth to the west to repeat the process. With 3 Plate Solve solutions the Seestar will update its pointing model and then center the desired object. With the Horizontal Calibration routine turned off, the Seestar has to rely on its compass and level only to find the desired object. With Auto Focus turned on (default setting), the Seestar will automatically perform a focus routine when it goes to the first object after being turned on. The focus routine works very well and I have not found the need to do a manual focus. But, if you want to you can enter the manual focus routine on the previous page and set the focus position manually to try and improve the focus. It should also be noted that it is a good idea to force the Seestar to do an auto focus as the temperature cools down during the night. Some people like to focus for each new deep sky object. To do that use the focus button on the right of the screen during a Live View (see later). Take note of the Adjust Level button on this page as we will need to use this each time we set up the Seestar for a viewing session. Nightly Setup Procedure A typical viewing session begins by placing the Seestar outside on its tripod on a relatively level surface free from vibrations and wind, both of which can be a cause for poor star images resulting in failures in the stacking process. Keep the Seestar as low to the ground as possible for better stability, but if you must elevate it to see over obstacles use a sturdy tripod. The tripod from a telescope you already own is a very good option, although it will not be as light weight and compact as a camera tripod you can purchase on Amazon. An extremely helpful optional accessory is a 3 point tripod leveling base which fits between the Seestar and the tripod. It is much easier to level the Seestar using the three leveling knobs on this than trying to adjust the height of the three tripod legs. But either method will work. Next, power on the Seestar, open the App and Open the Seestar arm. Go to the page shown below to perform the Adjust Level operation which can be reached from the Advanced Feature page by clicking on the Calibrate button. The Adjust Level operation should be performed each time the Seestar is moved to ensure that it set up in a level position which helps improve the accuracy of the initial GoTo procedure. Pressing on the Adjust Level button brings up the following screen which provides feedback to help achieve the optimum level. As you adjust the level two Green Circles will either overlap more or less depending upon whether you are improving the level or not. Adjust the leveling knobs until you have the best overlap you can get, typically a number less than or equal to 0.3 should not be difficult to get and should provide satisfactory results. Once leveled you can set the exposure time and indicate whether you want to save each individual frame as a FITS file for subsequent post process or not and then go back to the Apps main page to select your target for live stacking. Be aware that longer sub-exposure times will likely result in more dropped frames due to star trailing, especially when pointed at Altitudes greater than or equal to 75 degrees, as well as, to Azimuth angles close to 0 and 180 degrees as these are the locations where field rotation is maximum. ![]() Routine Operation Once the setup procedure has been completed it is time to pick a target. For best results, try to stick with objects which will be between 30 and 70 degrees altitude for the duration of imaging. Objects higher than 70 degrees will begin to exhibit greater field rotation which will result in more rejected frames. Objects below 30 degrees are viewed through a great deal of atmosphere which can make for more distortions and also rejected frames. All-in-all the Seestar requires overhead to analyze each sub-frame and decide to accept or reject it, stack the image and dither the mount discussed later) which amounts to as much as 25% of the total imaging time. So, expect to be able to stack no more than 15 min of exposures in 20 min if the Seestar tracks perfectly, the skies are perfectly clear and steady, there is not wind, etc. More often than not we do not have these ideal conditions so expect stacking efficiencies as low as 40% with 75% as a maximum when measured as total stack time divided by actual time elapsed. The Stargazing and Solar System pages provide lots of helpful information to guide you in selecting deep sky or solar system targets, respectively. If you tap on Stargazing it will bring you to another page which displays some of Tonight's Best deep sky and solar system objects which are visible that night. You will also find Tabs for specific Deep Sky Objects such as Galaxies, Nebulae, Star Clusters, etc along with a Solar System tab. Selecting one of Tonight's Best or one of the Solar System objects opens another page which gives detailed background astronomical information about the object. Selecting Galaxy, Nebula, etc under Deep Sky takes you to a list of those objects. If you click on the "GoTo" icon to the right the Seestar will immediately go to that object. If, instead you click on the name of one of the objects you will go to a page with details about that particular object, including a plot of its Altitude over time which is helpful for deciding when it is best to view the object. At the bottom of this page is the red Go Gazing button which will direct Seestar to GoTo the object. If you do not see the object you want you can type the name or astronomical designation in the search at the top of the page. Or, tap the red Skip bar at the bottom of the page to go directly to the imaging page. The Seestar App also has a nice Sky Atlas which can be entered by pressing on the "SkyAtlas" icon on the bottom of the Home Page. This works like a typical Sky Atlas program with buttons on the right column to find "Objects", turn on the "Compass" to allow the view of the sky to rotate as you phone/tablet does, a "Grid" button to turn On/Off the sky grid, a "Ground" button to show where the horizon is, and a "Framing" button to set up the Mosaic feature which we will discuss later. Now here is where the Seestar takes makes EAA really easy. Once you tell Seestar to go the object you selected, it slews to the point in the sky it thinks the object should be located. It is able to get close to the object because the compass calibration lets it know where true north is positioned and because it has been leveled. Most likely it will not have the object centered in the field of view, but in most cases it should be visible unless the object is very dim. Now, the Seestar will automatically go through its Horizontal Calibration process where it takes an image at the GoTo location, rotates the mount 15 degrees in one Azimuth direction to take another image and 15 degrees in the other Azimuth direction to take another image. Seestar then plate solves all three images refining its model of the sky so that it can next move the mount to the correct location to center the desired object in the field of view. In my experience, Seestar does an outstanding job in this regards. If you have trouble with this operation, check your level. If you still have trouble you many want to redo your compass calibration and your level training. After it centers the object it will perform the "image enhancement" which means that it takes 5 ten second dark frames and combines them into a single Dark Master which it will seamlessly subtract from all individual light frames to remove the fixed pattern background noise. Next the Seestar performs an automatic focus and then it begins the image capture and stacking. The Horizontal Calibration and Focus routines are only performed on the first object viewed. You can force a focus any time you want by using the focus button on the right column of the live view screen. Prior to beginning the image sequence, Seestar will place either the internal Dual Narrow Band or UV-IR filter in front of the sensor depending whether the object is an emission nebula or not. The former is only useful for emission nebula, while the later is useful to minimize star bloat. The user has the option to tap the filter Icon in the upper right side of the screen to move the Dual NB filter in or out. If it moves the NB filter out the UV-IR filter will replace it. The image above shows the imaging page which appears after selecting GoTo for any target. A preview of the image will appear in the center. On the right are buttons to turn On/Off the Filter, Adjust screen brightness, Mark, force an Auto Focus and go to the Sky Chart. The red button at the bottom turns On/Off the exposure. Pressing it will begin an exposure and the live stacking process. Tapping the small white circle in the center of the screen will bring up the Joy Stick button shown in the image above which provides the ability to move the mount left/right or up/down to change the position of the object in the field of view. The Sky Chart button takes you to the a celestial chart which shows the field of view overlaid on the chart along with identification of key objects on the chart. You can use the Sky Chart to move the mount around to different locations in the sky as an alternative way to move to different objects in the sky or to fine tune the image in the field of view. Live Stacking
Once the live stacking process has begun, the Seestar will take successive exposures according to the time set (10s, 20s, 30s) and continue to stack them until you hit the red imaging button at the bottom of the screen. Once you tap that button Seestar will save a jpeg file to you phone or tablet of the stacked image and save a Fits image of the same to the Seestar memory. If you tap the red imaging button again you can continue to build up the image or stop and start of new image of the same target or go back in the App and find a new target. A countdown timer appears at the bottom of the screen during the imaging process counting down the individual exposure time. As successive images are added to the stack the timer in the upper right will add to the total stacked time. When an image is deemed not acceptable to stack by the internal software either because of star trailing or other poor quality the stack timer will not be advanced for that frame. Typical stacking acceptance rates vary from roughly 40% on up and are impacted by the object's altitude, azimuth, the seeing conditions, high thin clouds, wind or any other sources of vibration. The higher the altitude the more likely to loose frames due to the effect of field rotation so most users stay between 30 and 75 degrees in altitude to get the best stacking efficiency. The Seestar also has an automatic feature called dithering which is used to minimize the impact of fixed pattern noise. After every 5th frame the Seestar will move so that the image is shifted by ~30 pixels in the frame to shift the fixed pattern noise around so that it is averaged out in the final stacked image. This dithering takes time along with the internal stacking of the frames so that there is an overhead of ~20 to 25% of the total time. Hence, even if you were to achieve 100% stacking success, you will still only get 45min of stacked image in a total time of 1 hour. Seestar Pros and Cons Based upon my experience with the Seestar and many other scopes over the years, I would call the Seestar the simplest scope to begin obtaining dramatic images of deep sky objects in your first night with it with no prior experience required. It is truly as simple as setting down, leveling, connecting the App and telling the Seestar to go to whatever object you want to image. It is light weight and compact making it amazingly portable and quote practical to take on an air plane. And the cost, at $499, is at least 1/3 of what it would cost to put a similar setup together on your own. The other nice thing about the Seestar is that ZWO continues to update the software to add new features and improve upon the existing ones. Recently they introduced the Plan Mode which allows us to set up an imaging plan ahead of time and then allow Seestar to start the plan on its own at the preset time and finish own its own. You can set it up and go to bed and look at the captured images the next morning. They are also planning to add an Equatorial Mode in another month or two which will add much more capability at the cost of having to do a Polar Alignment. As far as the Cons with the Seestar, it would be nice if it had a better imaging chip which could provide sub 2 arc-sec per pixel resolution and a larger field of view. But of course, this would add cost so it is only a relative Con. All-in-all I can highly recommend the Seestar S50 to anyone wanting an almost fool proof tool to capture dramatic images of what the universe has to offer. You can watch my Seestar Tutorial video with step by step instructions on how to set up the Seestar and begin taking images you first note. You will find it here www.youtube.com/watch?v=x3TXn5GT8SQ If you are interested in a Seestar, either the S50 or the smaller S30 please consider using my affiliate links below for your purchase. It will not cost you anything and will provide a small commission which helps to support my web site. High Point Scientific Seestar S50 bit.ly/3YL9aoY Seestar S30 bit.ly/3WR9sJg Agena Astro Seestar S50 bit.ly/4fISCUP Seestar S30 bit.ly/4gB2xLn
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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. ![]() 4B. Not Enough Stars Detected For live stacking to work, the software needs to detect at least 3 stars in each image to be able to shift and rotate frames to align to the first image frame. That is not to say that alignment will always work or even that it will do a good job with just 3 stars as that is the bare minimum required to compute the necessary adjustments that need to be made. Sharpcap specifies that 10 - 20 stars with good distribution across the frame are required for the best possible stacking to proceed. The user can set the number of alignment stars under the "Alignment" tab. Defaut is 15 stars. You may not be able to see the stars yourself even though Sharpcap can. But, you can check the number of stars detected in the "Alignment" tab under "Star Detection Status". If not enough stars are being detected there are several quick things to try. 1. First, increase the exposure and/or gain. If the exposure is too short the camera might not capture enough stars in parts of the sky where the number of visible stars is small, such as pointing away from the galactic center. 2. Check the focus. A poor focus will make stars dimmer and harder to detect, as well as, broader and less star like. 3. If both of those fail you can try adjusting the Star Detection parameters. While Sharpcap automatically adjusts the Sensitivity (up if less than 25 stars are detected; down if more than 200 stars are detected) you can still try to see if this helps. Increasing the Noise Reduction setting helps with star detection when the overall image is noisy and when hot pixels may be causing a problem. Lowering the Maximum Star Size measured in pixels can help prevent small deep sky objects from being misidentified as stars. Suppress Hot Pixels is a default setting which will help to prevent hot pixels from being identified as stars. It's default setting is to be checked. If there are obviously faint stars not being detected you can try checking Optimize for Faint Stars. On the other hand, this can also cause non-star objects to be falsely identified as stars so if it is turned on and you are having trouble stacking and nothing else seems to work, try turning it off. Highlight Detected Stars is a good trouble shooting tool to see what and where stars are detected. A yellow highlight indicates a star used for stacking while a red highlight indicates stars not used for stacking. 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. 1E. Check The USB Hub If the problem is with the hub, check other ports on the hub to see if one of them works. On many hubs some ports are USB3 and some are USB2 while others work with both types. If you cannot get any port on the hub to work, replace or eliminate the hub. The ideal connection is to avoid a hub if at all possible and connect the camera directly to the computer. But this is not always possible. 1.F Check the Computer If the camera still does not connect try another USB port on your computer. If it still does not connect try rebooting. You can also try a different computer if you have one. 1G. Check the Software One day I found that I could not get The Sky X software to connect to my camera. It had connected without issue previously, but for some reason it stopped. I could get the camera to connect using SharpCap and ASILive but not The Sky X. I tried the above troubleshooting tips but in the end found that the solution was to completely uninstall The Sky X and reinstall it. That solved the problem. So, whether this was a problem with an updated version of The Sky X or a Windows update I will likely never know, but at least I am back on track. 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. ![]() Installing Hyperstar Removing the secondary mirror from your SCT may sound scary but it really is a simple matter. I like to set the OTA at a slightly elevated angle so it is easy to reach the secondary and gravity will still help to keep it in place when its retaining ring is removed. The secondary slides out and can be placed into the protective holder which comes with the hyperstar. The hyperstar is threaded onto the secondary holder. But be careful not to over tighten the hyperstar. Finger tight is sufficient. I once got the hyperstar so tight that I had to remove the corrector plate to get it back off. You should not have this problem if you do not over tighten the hyperstar like I once did. After installing the hyperstar several times you will even feel comfortable doing this in the dark. The procedure should take only 5min or less. While hyperstar can weight as much as 3lbs for the 14" SCT it is not going to damage your corrector plate when handled carefully. An SCT corrector plate is much stronger than one may realize. Still, I would never transport an SCT with a hyperstar installed as the possibility of banging into the hyperstar is always present. Also, when covering the telescope using a hyperstar with an all weather cover just be careful that the cover does not snag on the hyperstar which protrudes from the OTA. I leave my hyperstar on for multiple days while in the field using a dew shield and cover over the hyperstar and correct which keeps dirt and dust off the corrector. At home I leave my hyperstar mounted on my SCT in the backyard observatory as long as I plan to work at f/2. There is really no need to remove and re-install hyperstar every day. ![]() Hyperstar Collimation Just like the secondary mirror on an SCT, hyperstar will need to be collimated from time to time. Fortunately, hyperstar seems to hold collimation just as well as a secondary mirror so you should not expect to need to collimate any more frequently than you do without it. Also, you most likely will not need to re-collimate your scope when you put the secondary back since it is indexed to the optical axis with a pin which fits into a notch in the flange which holds the secondary. Hyperstar has 3 sets of push/pull pins located at 120 deg increments around the outside for the purpose of collimation. There are two strategies for initial collimation. The simplest takes advantage of the high precession machining of the two hyperstar mechanical bodies. Just adjust the push/pull pins so that both flanges of the hyperstar bodies are in contact all the way around and then tighten the pins. So long as these two flanges are parallel to one another and the corrector plate is aligned with the primary mirror you should have good collimation. Several folks have reported that this has worked for them so it is worth trying first. If you are not satisfied with the collimation with that approach you can use the second method. With this approach you will need 3 shims 30 to 40 mil thick. Metal stock of this type can be found at your local Ace hardware or online. I use Cu stock which I cut into 3 pieces long enough to fit between the two hyperstar flanges. With the shims spaced 120 degrees apart between the two hyperstar flanges, tighten the push/pull pins just enough so that you can barely pull the shims out. Make sure that you tighten pins are engaged so that the flanges do not come loose. Then, under the stars perform a collimation as you normally would using the push/pull pins in the same way as you would the 3 screws on the back of the secondary mirror. You will find that it is a lot easier to adjust the push/pull pins with your fingers. Just make sure they are all tight when you are satisfied with collimation. A very large variety of cameras are compatible with hyperstar including those from ZWO, QHY, ATIK, SBIG, etc. When ordering the hyperstar element you will need to specify the camera that you will use with it since a camera adapter is required to attach the camera to the hyperstar lens at the optimum distance from the camera sensor. ![]() 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. ![]() EBL Solar Apollo While EBL is not as well known of a brand in the power station and solar panel business, it has been around since the 90s as a manufacturer of alkaline, NiCd and other types of batteries and chargers. A major appeal of the EBL Solar Apollo 100 is that it is one of the least expensive 100W panels at $149 which is almost half the price of the Jackery. The output voltage of the EBL panel is 20V at 5A which works out to 100W. The EBL is about 23% larger than the Jackery when fully open with an unfolded dimension of 46' x 26.75". It is only slightly larger than the Jackery when folded with a dimension of 26.75 x 23 but that still makes it less convenient to pack for travel compared to the Jackery. It also has convenient built in carrying handles and magnets to help keep the two halves together when closed. The EBL panel weighs 9.5lbs. I wish EBL had made the two kickstands wider like the Jackery as theirs are only 4.25" wide which makes it a little bit harder to support given the larger overall dimensions of the panel. This panel is also coated with a plastic material to make it more durable and easier to clean and is splash resistant but not waterproof. Just like the Jackery the EBL has a zippered pouch which houses the output cables connected to the panel. However, the EBL panel uses a pair of 3ft cables with MC4 connectors on the ends. I found the short cables to be stiff and therefore difficult to manipulate. But they do supply two additional flexible adapter cables, one which converts from the MC4 connectors to a Power Pole connector and the other to a 5.5mm x 2.1mm connector. Plus they include 5.5mm x 2.1mm to 8mm, 5.5mm x 2.1mm to 5.5mm x 2.5mm, and 5.5mm x 2.1mm to 3.5mm x 1.5mm adapters so that the Apollo panel can be connected to pretty much any brand of portable power station. Unlike the Jackery, the Solar Apollo panel does not have a USB charging port. But much more importantly it does not have a rigid strain relief where the cable connects internally to the panel like the Jackery. Instead there is a simple loop which was not enough to prevent one of the cables on the panel from partially coming out of its internal connection exposing a bare lead. The panel comes with a 1 year warranty and technical support is available only through China. ![]() 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 |
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