 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 natively supported by Sharpcap  Cameras TSX Natively Supports 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.
0 Comments
|
Categories
All
Archives
August 2024
|
RSS Feed