9.33
...
·
·
31
likes
|
|---|
| (deleted) |
9.31
...
·
·
5
likes
|
|---|
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.
|
9.33
Topic starter...
·
·
1
like
|
|---|
| (deleted) |
0.90
...
·
|
|---|
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.
|
|
9.31
...
·
·
5
likes
|
|---|
I always do darks every session. 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. |
14.24
...
·
·
2
likes
|
|---|
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. |
4.51
...
·
·
2
likes
|
|---|
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. |
9.33
Topic starter...
·
·
2
likes
|
|---|
| (deleted) |
|
9.31
...
·
·
2
likes
|
|---|
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.
|
7.16
...
·
·
5
likes
|
|---|
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 |
1.91
...
·
|
|---|
This is a really good thread. Too bad I am seeing it just now. I have often wondered if I were to start this hobby all over again, what would I have done differently? I learned a lot from experiments that didn't go so well. When I started seriously in 2013 with a DSLR camera, I could not find software at the time that did automatic stacking on macOS. I used to MANUALLY stack images pixel-by-pixel in GIMP at first and then Photoshop Elements. It was a very tedious process to be sure! Thankfully, I use Siril now for automatic stacking, mostly for solar images, but sometimes for lunar images or when experimenting with old images. I have spent many nights trying to get decent images contending with light pollution and doing processing acrobatics to get a decent final result. I have had some successes, but a lot of times, the images were too washed out to show anything more than a shadow of the glory of the star field. All-in-all, I don't regret the experiments I did and the path I have taken, but if I were to start all over again, I would just stick to photographing the Sun and the Moon because they are the most rewarding objects to me where I don't have to contend with light pollution. |
8.11
...
·
|
|---|
Jan Erik Vallestad: Are you saying you never change the camera rotation? How do you control the composition of your images without rotation? |
0.00
...
·
|
|---|
Light flats need to be done each session. That's where camera rotation matters. It's only the darks and dark flats that can be a library. They're blind to camera angle. (and the bias and BPM) I'm loving the dark library from last November's rainy spells. Such a time saver. If I try out a new gain or exposure or camera temperature, I make a new set of darks just for the session, stack them and add the master to the library. Thank you Francois for the nicely thought out, concise and realistic list. Bravo. Especially 17 (have fun with it) |
5.76
...
·
|
|---|
The camera doesn't know it's been rotated. Previous flats will work fine.
|
|
4.51
...
·
|
|---|
Tony Gondola:Jan Erik Vallestad: Well, never is a long time but rarely enough that it won't really matter since I'm trying to pick targets to shoot for a long time. I can manually rotate with my refractor but it comes with huge drawbacks unless i add another piece of equipment, which I can't really fit atm. Basically the scope has no proper built in mechanism for it so it involves manually loosening the entire imaging train, moving a couple of rings on the focuser tube, and then re-tightening it. Last season I didn't rotate the camera at all, but then I also spent about 230 hours on the same target. I did two sets that lasted most of my season and only swapped things around at the very end when astronomical darkness had passed really. So as long as I see myself doing long integrations I can't see any benefit of rotating very much. |
9.33
Topic starter...
·
·
1
like
|
|---|
| (deleted) |
|
1.91
...
·
|
|---|
@Francois Theriault After all of your experience, what would you say is your proudest accomplishment? I just finished going through 11 years of my past astro photos and posted many of my best ones as well as my struggles. For me, solar is my proudest accomplishment. I found white light solar imaging very challenging to process, but after much experimentation, I developed an optimized workflow. This is my proudest accomplishment:  The Sun - May 09, 2024 My second is the untracked Milky Way because I developed a very powerful noise reduction technique workflow that made a night and day difference:  Noise Reduction Third would be spectroscopy of bright stars because I can see what elements are present in their atmospheres:  Betelgeuse Spectrum Almost everything I did was through regular camera lenses, but I did take some images through my telescope, for example a clear image of Saturn's rings:  Saturn in 2016 Steven |
9.33
Topic starter...
·
·
1
like
|
|---|
| (deleted) |
8.34
...
·
|
|---|
Arun H: Generally agree. What I do is set up NINA to take darks every time in the morning after the roof closes for an hour or two. These are used to keep dark libraries up to date and are not necessarily the darks for the session I have done that night, rather for darks times and/or temps that I commonly use but where the subs are getting somewhat old. I like to have libraires of dark subs that are not more than maybe 6 months old from which I can make fresh masters. |
|
5.76
...
·
|
|---|
I wouldn’t underestimate the value of darks. Skipping this step will become obvious in processing very dim objects. Bringing out detail in dark areas is not possible without such calibration frames. It’s true that noise might not be noticeable on bright targets. But dark nebula and faint gasses like sodium and oxygen are often buried in noise that can be greatly reduced with dark frames.
|
