StuartT

not much different, if truth be told!

Ok, so this is interesting. It's really looking like in my setup, stacking with no calibration frames is producing the best result! The first image is with darks, flats and flat darks. The second image is without any calibration frames. So just the lights stacked. Both are just as they come out of Astro Pixel Processor and before any post-processing. I'm also attaching the FITS for each one, in case any of you want to see what you can get out of them. Cygnus_Wall_with_L-extreme-RGB-session_1.fits Cygnus_Wall_with_L-Extreme-RGB-session_1_no calib frames.fits

this is helpful, thanks. And you said (above) that bias frames are also not needed with this camera? Why is that?

I must admit to being pretty confused about which calibration frames I am meant to be doing. Someone also said (somewhere here in SGL) that with a cooled camera like the 2600MC you don't really need darks either. Don't know if you agree with that? Oops! So it is. 🤦‍♂️ Ok, so I am going to try stacking without any calib frames (as I sometimes find this makes things even better), then also with just darks, flats and darkflats. I'll then post what I get and also the FITS (but the correct ones!) But I don't really think I know what I am doing in Astropixel Processor to be honest. I am just using all the default settings and pressing the buttons 🤣

you definitely don't need to get down to a few arcsec of polar alignment. 1 arcmin would be pretty good and 30 sec would be pretty excellent. Unless you have a long focal length main scope you really don't need to fuss too much. What is your main scope's focal length?

Last night I collected almost 3 hours on Cygnus Wall using my new Optolong L-Extreme filter. I shot bias, dark, flats and darkflats. I stacked in Astropixel Processor using the default settings then I used the Astroflats Pro plugin in Photoshop then the Gradient Exterminator plugin in Photoshop finally a bit of contrast enhancement in Photoshop Here is what I ended up with. I think it's quite nice but I am not sure if there is more in there (so I have provided the FITS also, in case anyone wants to try it in their workflow)

this has all been super helpful. Thanks SO much everyone. So, if I have daytime light leakage --> do flats at night cheap Amazon tracing panel gives uneven illumination --> bite the bullet and purchase the geoptik flat generator panel Decision! 👍

ok, so just point up at sky (4pm, well away from any sun) and with my new perspex gizmo on top. Here is what I get. (rotating the gizmo does not affect the pattern of vignetting) I've adjusted the exposure to be more 1/3 to 1/2 of the histo)

I also use SharpCap to polar align (though the new PA tool in NINA looks much nicer, so I'll prob switch to that). But I am not using a guide scope for PA, I actually use my main scope only (808mm FL). Even though it can only see about 1 degree x 1 degree of sky, the SharpCap routine work just fine. I agree with @MCinAZ that chasing perfection is rather pointless. If I get down to 1 arcmin of PA error, I think that's fine and I stop there. Prob even 2 arcmin is fine.

Hmm.. interesting. I am not aware of one corner of the resulting image being dark. By the way, do you know what is causing the two or three circular artefacts of slightly darker green? But I am learning a lot about flats, so I hope to get better at this. I have in fact just made myself a gizmo to make daylight flats with the scope pointed to the zenith. Two sheets of perspex with cloth between.

I just watched one of Cuiv's youtube videos and noticed that he uses something called GS Server (https://sites.google.com/view/greenswamp/) instead of EQMOD for scope control (tracking, mount limits etc). I'd never heard of this before and wondered if any of you guys use it? What is are the advantages? Thanks

I tend to find my images look better without the flats added! (so presumably that doesn't say much for the quality of my flats - as they are supposed to improve the image, right?) I've also tried using a tracing panel from Amazon, but the light was just too uneven. I'm reluctant to shell out £250 for a fancy flat generator panel, but maybe that's the only way? Surely this shouldn't be this hard?

thanks everyone. Unfortunately, the windows recovery tool found nothing. I purchased a license to a highly recommended tool called EaseUS, but it's not looking too promising. A whole night wasted. Oh well... lessons learned, I guess

ok, but won't installing that overwrite things?

On my hard drive and windows 10

I just managed to erase all my lights from last night! Two hours of data... 😭 Can anyone recommend a good file recovery program?

Last night I got a good session of a couple of hours on a DSO. I left the whole rig as it was and this morning I did my flats by pointing to the zenith (fully overcast sky) and stretching a white t-shirt over the aperture. I then used the flats wizard in NINA. But I seem to have a gradient. Is that right? Shouldn't flats be.. well.. flat?

this is turning out to be a very interesting and informative discussion. I'm learning a lot! Just in praise of shorter subs... as long as you have a decent CMOS camera I am finding that shorter subs work just fine. In my case 35s sec being the limit of my mount (because I basically CBA with guiding).

oh wow! this is great! so now it sounds like I can dispense with both bias and darks (as I have a 2600MC Pro). So I really only need to do flats and dark flats. Excellent!

Hi there. Yes. I did thanks. It works fine now. It turns out that most of the gear I have connects fine via USB, but the mount requires a serial connection (because it uses ASCOM which is quite an old fashioned interface). So here is what I do. plug in the cable to the ultimate powerbox run device manager to see what number it has assigned to the COM port (this changes each time) in NINA connect the scope, after first changing the COM port with the gear icon to the number shown in device manager Then everything else connects via NINA (focuser, dew heaters, camera etc) Took me a bit of trial and error, but it does at last work!

And presumably, darks can just be built up into a library (provided the temp and gain matches)? So only really flats and dark flats need doing then and there (before dismantling the rig, I mean)?

thanks. I think the flats were shot ok. I used the flat wizard in NINA. But they were from a diff session with the camera removed in between. So I guess they didn't match well.

interesting that you don't use darks. I wonder what the order of importance of the various types of calibration frames is? i.e. which type are the most important to get?

yes, I'm beginning to wonder if calibration frames are all they're cracked up to be. I think I might try my next few targets without any and see how I get on

Thanks for the shout out 🙂 Pleasure! Look forward to seeing what you get. I only use 35 sec subs with my 2600MC Pro, as I have not reached the stage of guiding yet...