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| 17 things that I did in the last year that improved my astrophotography. Hi, I am an amateur astrophotographer. I have spent about 10 years doddling with it, even taking a 3-year break during the pandemic due to work commitments. I came back to it in spring of 2023 and found a different world in astrophotography that I had remembered. My reality is that I image from my backyard in a suburban area. My sky is Bortle 7 to 8. Lots of light pollution. I am surrounded to the North by our local Costco, to the East by about 10 car and heavy equipment dealership and to the South by the light dome of city center. Thank goodness for understanding neighbors that turn off their back porch light whenever the weirdo next door is out with his telescope.E Even with these conditions, I enjoy capturing and processing my images to the best of my ability.Here are the 17 best things that I did in the last year to greatly improve my astrophotography (not in order). 1) Switch to N.I.N.A. for image capture. This is a great piece of software and once you learn it, it can be a real satisfying experience. It simplifies the meridian flip. The plate solving is a real game changer. 2) Never image lower than 35° above the East/West horizon. In my case, there is too much light pollution the closer I go to the horizon and it is just a waste of my time. This means that I have to image 2 to 3 targets in one session and do it several nights in a row. 3) Try to gather as much data as you can on a single target. I aim to gather a minimum of 4 hours and will do 10 hours if I can – weather dependent. This improves both the signal and the details that can be captured. 4) Understand the pixel ratio of your telescope / camera setup. That ratio can be calculated by (pixel size of the camera / focal length of the telescope) x 206.265). This gives you the Arcsecond per pixel of your setup. Anything between 0.7 and 2 (in my case) is good. These numbers will change for you depending on your location and local seeing conditions. But in my case, lower than 0.7 is oversampling (bloated stars, loss of detail) and anything over 2 is undersampling (blocky stars). This simple calculation determines if you should be binning or not. A good site to get more information is www.astronomy.tools. This calculation applies to both the imaging setup, but also the guiding setup as well. 5) Do a good polar alignment. I am to the sub-arcminute for polar alignment. Does a great improvement to you autoguiding. I went from 3-4 arcsecond autoguiding to 0.5 arcsecond autoguiding. At long focal lengths, it makes a world of difference. 6) Always match your autoguider scope to your imaging scope. The unwritten rule is never use a guide scope with shorter focal length 10x less than the imaging scope. I try to aim at 5x or less. For example, my RC is 1625mm focal length. My guiding scope is 430mm focal length, or 3.78x. 7) Really understand Pixinsight. Will anybody ever really understand Pixinsight – I doubt it. However, it is important to understand the processes that I typically use for both pre and post processing. 8) Really understand the color wheel and different color combinations – interactions between one color and another. We deal with colors and transparencies. Sometimes leading to ugly images. It is useful to improve on color theory. For example to get rid of green – remove a combination of yellow and cyan (which makes green when mixed together). Also add a little magenta, which is the opposite of green and cancels it out to a point. 9) Really understand stretching and curves, especially the concept of overstretching (too much signal) and clipping (loss of signal). GHS in Pixinsight is a great help for this. 10) Learn to trouble-shoot. I have spent my share of nights at -20°C freezing in the dark cold wondering why my autoguider would not talk to my computer, or why the plate solving was not working, or why my telescope would overshoot and crash into my mount. Same in the summer at +30°C, getting eaten alive by mosquitoes. The lesson here is to have patience and try to trouble-shoot items one at a time. It could be the wrong parameter in the software, a faulty cable, a bad power supply, etc... We all have been there. 11) It is not the equipment you have, it is what you do with it. Except for 2 exceptions, all my gear is about 10 years old. Most of it was bought used. Still going strong and I plan on to keep working with it until it fails or becomes unusable. 12) Know your targets and use the correct telescope to capture it. I have 3 main imaging scopes: A refractor with 430 mm focal length f/6. I use it for large targets like the Rosette or the Heart nebula. My second is an 8-inch Newtonian 800 mm at f/4 for middle range objects. I don’t like to use this one because my subs end up to be about 15 seconds on LRGB. My last one is a Ritchey Chretien at 1625 mm focal length at f/8, which I use for deep sky objects. I too have suffered from aperture fever and bought a lot of gear which ended up in the corner, unused. I have settled on the 3 telescopes listed above as a good all-around compromise to capture all of the targets that I want to capture. 13) Because of light pollution, I turn to Narrowband Imaging a lot as I get better results. During galaxy season, I don’t have any choice than to do LRGB. I sometimes use my old trusty Canon 60D (unmodified). 14) Scope out your targets. Use these atlas – you might find a little known NGC or Sharpless object that most people miss. Use programs like Stellarium. Use sites like Telescopius that allow you to visualize your target with your telescope / camera combination. Do your research and get better results. 15) Learn to no overdo it in processing. Sometimes less is more. Learn to say – this is enough, I am satisfied with the result, let’s move on. 16) Always, always, always capture flats and darks for every session. It makes a world of difference in the processing and error correction and gradient removal. 17) Enjoy yourself. Have fun with it. This hobby is not for the faint of heart, but it is very rewarding. |
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| Great advice. Only minor disagreement is on point number 16. You don't need to get darks every session if you have a cooled camera. Just build a one time library of darks for your sensor at typical gains / offsets and temps and use it for 4-6 months. |
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I always do darks every session. I sometimes decide to do 150 second exposure at 75% gain instead of my regular run because I have a brighter object or to take 300 second exposure at a higher gain for a dark target. For LRGB, I sometimes deal with 15 second exposures due to light pollution., sometimes I can go 30 even 60 second exposures. I cannot possibly take a library of darks for all these combinations. That is why I do not use libraries. I understand that at a nice dark site, one an build a nice library of darks because the conditions are relatively stable. Not for me in a light polluted area. Cooling is an issue as well. During the winter, when it is -15° for me, the camera will NOT cool. Nor does it need to... In the summer time, sometimes the camera cannot keep up with the cooling. For that reason, I only cool to -10°C below ambient. That seems to work best for me. |
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| Nice list ... I would say that for most targets though - I collect bare minimum 15 hrs, and aim to have 30-40+ (I've gone up to 50). More data is ALWAYS better. Because of such extended times - I do not gather flats for every session - just when updating or cleaning the image train. Any minor issues that crop up re: flats can be processed out. |
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Francois Theriault: If I had to take twenty 300s darks ever time I did a narrowband target, that is 1.5 hours wasted every single session for no reason. Really no need to do that and no need to burn yourself out. Unless the light pollution is changing so drastically from one session to another, you shouldn't change your exposures that much. You can do 15s, 30s, 45s, 60s, 300s darks one time, and then create master darks and just store them. I mostly use gain 100, and sometimes use gain zero with my 2600mm. Otherwise I don't change anything. Again you do whatever you like, but there really is no benefit to wasting that much time on taking darks every single session. There are bigger fish to fry. |
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Ashraf AbuSara: I would have to agree. Of all the things to do, taking darks every session, with a cooled camera, is the least value add thing you could be doing. It should be quite possible to come up with a workable exposure strategy that allows you to use a library of darks that you construct once or twice a year. It is one of the main benefits of a cooled camera and imaging from a light polluted site should not change this. |
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It's great that you've identified areas to improve and learn on, we are constantly growing. I made several changes to my approach before last season as well. I use the AA+ for controlling my setup so everything from focusing, PA, platesolve etc works pretty flawlessly. I've not yet seen any real reason for me to change to NINA, unless it were to be able to synchronize several setups on the same mount. As for exposure lengths I agree with Brian. When I started I had the same "fever" as most people starting out. Hitting new targets all the time after 2-4 hours and calling it a day, then wondering why my images were blotchy and not so clean. So I'd argue that one of the bigger improvements people can do is to really up the total exposure lengths. The most recent season I dedicated most of my imaging time to one single target which ended at more than 229 hours. The amount of details you resolve is pretty astonishing. Generally I try to do 20 as a minimum now, but mostly I find myself wanting a bit more. That being said, bright popular targets don't necessarily need much time, depending on what your goal is, M42 and NGC 7000 to mention a couple obvious ones. The first thing I do at the start of the season is making a dark library. 15s, 30s, 60s, 120s, 180s, 300s, 600s etc. I only redo flats when something has changed or I notice a neccesity for it (which rarely happens). I chose to image with the camera cooled to -20 the entire season, except for some minor stuff I did after the season initially had ended. Like you I have extremely cold winters, -15 would be ok temperature-wise. Luckily I got away with -20 the past year but ambient temps at -25 or colder isn't unheard of. The cooling always works though, the reason I choose to utilize it is to always make sure my calibration frames are matching properly. If I would need to cool more I would do new ones of course, but -20 seems to work regardless as long as the change isn't too drastic. The AA+ is a champ though. I store everything "indoors" in ambient temperatures, for long periods of time while out in the elements it freezes over and nothing fails. The only thing I do is cover it with a jacket to keep the frost off the main components while they're not powered up. When powered they generate enough heat to keep it away on it's own. As for never imaging below a certain degree above the horizon I would say it depends. If I were to follow that rule I would never have gotten any images of 12P/Pons-Brooks, other times certain objects may never rise above that degree. I too have a bit of LP to the west so I understand your reasoning though. But for certain scenarios you take what you get. |
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| I would absolutely love to take 30 hours of data on a single target. However, we have had a total of 12 clear nights here since January 1-24. A bit hard to take that much data. We do with what we can collect , unfortunately |
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| Clear skies are a luxury for most backyard astrophotographers. We just have to accept that sometimes, we just have to work with what we get. |
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Hi Francois, reading through your list is like reading in the past. At least it feels that way. I'm glad I figured out most of the things myself. The other ones I am at least still working on. But I'd like to add maybe one thing to the "Trouble shooting" section. Looking back, it did take a long time to find out the reasons for some behaviors and there was a learning curve one can avoid. 1.) No matter if you use a portable or a permanent setup. Take your time to think your setup through. Build an imaging rig and stick with it until you really know how it works. Change things one after the other and get used to the new stuff. Don't do too much at once. 2.) No matter what equipment you use, make sure you have a really sturdy power supply. Leave some headroom so it can deliver more power than you think you need. Especially in really cold conditions you may reach the limit of it. I can't tell how much problems I had, because there was simply not enough power. Use power wires with a descent gauge so they are able to carry the current you need. Otherwise the voltage can drop and you will have strange behaviors that happens now and then. You will have a really hard time to figure out what's the problem. Here are some examples: Every now and then, my imaging computer (in this case a Raspberry Pi based system) restarts. It happened occasionally and for a long time I could not figure out the problem. I lost so many data this way. It was solved after changing the power supply. Somehow, under heavy computing load, the power dropped below a threshold and the safety circuit on the board switches off the device. I now use Pegasus Astro power boxes and sometimes they switched off some ports, because the voltage dropped under the useful threshold. This happens occasionally, when conditions are "right" (especially in cold weather). The power supply should have been able to deliver the current I needed. The problem was the wires from the supply to the scope. I build another one with a larger gauge and since then all works without any problems. At least I was able to find a solution, but it took me a really long time and a lot of frustration. And I work in the electronics industry and should have known it from the beginning. Switch off the auto updates of your (Windows-) computer or at least set the use time of the PC to when it is dark. I lost so many clear nights because of updates I didn't realize. Always at midnight, the computer restarts and the programmed session was gone. I now set the use time from 10:01AM to 10:00AM. So updates will be done automatically at 10AM, when it isn't dark anymore. At that time the PC is usually off and after starting it, I can do things manually. That helped enormously. There are so many bad experiences I am able to tell, that it sounds like one can not enjoy astro photography anymore. But if your setup works (and mine does well now) you can concentrate on the fun things in life. Also my wife is happier now  CS Christian |
