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Processing flats with light files in SharpCap 3.2

Astrophotography
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#1 halebopp

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Posted 28 July 2021 - 05:06 PM

I've been imaging actively for about 2 years now but have never learned to do flats until recently. I use SharpCap 3.2 to do my stacking. My light frames are png files shot with the gain set to 350. A video I watched on YouTube said to shoot the flats as fits files and reduce any gain setting to zero (so I did) but when I put the lights and the flats into SharpCap, SharpCap could not process the two together due to incompatibility issues. Do I need to shoot the flats in the same format that my light frames are and with the same gain?

 

Also, when doing LGRB do I need to shoot flats for L and also each color? I can't find any info to guide me on this. Any help on these issues would be greatly appreciated!  smile.gif



#2 f430

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Posted 28 July 2021 - 06:33 PM

Yes. Shot Flats at the same Gain, same focus, and same camera angle as the Lights. Set the exposure time to get the brightness/ADU value you want for the flats. Say 25000/30000.

For Flat Darks, cover the scope/camera, keep same gain and shoot at the quickest exposure your camera will do reliably.

 

If your filters are really clean, you could probably get away with just shooting the L filter. But you'll probably get better results if you shoot all the filters.

 

Once you get setup, it doesn't take that much time.

 

I just noticed that your lights are PNG files, so don't know if the above is correct.


Edited by f430, 28 July 2021 - 06:34 PM.


#3 halebopp

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Posted 30 July 2021 - 05:02 PM

Ok thanks Viking. I'll reshoot the flats in png format and with the same gain as you mentioned. Everything else on the camera and scope will be the same as when I shot the lights. What about the color my flats produced? As I mentioned previously, my flats produced a very light green color image. Is that ok for a color camera or else what would be considered normal? I believe that learning how to shoot flats properly will be the single best thing I can do to improve a lot of my images.

 

Thanks for the info on shooting flats for LGRB too. I know how to shoot darks as I've been doing that for quite some time so no problem with that.

 

If anyone else can contribute to this topic I sure would appreciate it! I want to be the best that I can be even if it does take more time!  :)




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