Newbie question regarding flats

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PetePeterson
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Newbie question regarding flats

Post by PetePeterson » Fri Nov 20, 2020 12:49 am

Been running a new ASI2600MC with SharpCap for 3 months now and just this week upgraded to Pro. The Histogram color control and the FWHM focus routine are super, and I did manage to calibrate the camera as well. Have been doing astro photography and scientific imaging for 15 years and know how to use darks and flats. But I find the file system in SharpCap to be a puzzlement, and am having a problem figuring out SharpCap flats.

Here's what was supposed to be a flat taken last night: Image

It'd be really handy to know the file exposure time, temperature, gain used, etc in a file title as I've no idea as to what's located where and what it is. Am I correct in guessing that the software automatically finds the proper dark and flat file depending upon the camera setup?

Believe darks are functioning. But the image is of a 1 minute DSO exposure using a flat taken earlier in the evening (the bright glow in the center is a monitor screen reflection). For this exposure darks were turned off. Will be taking another set of flats ASAP but it'll be a week before the sky is forecast to clear once again. Any thoughts as to what I've done wrong here?

Feedback much appreciated.

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Re: Newbie question regarding flats

Post by admin » Fri Nov 20, 2020 9:56 pm

Hi,

that's certainly looks more like noise than a flat frame :-(

Below are a couple of screenshots that indicate what I'd expect you to see while first capturing a flat frame and then see after the flat has been captured and it when it is then being applied to each frame (assuming you haven't changed the illumination yet).

It's worth checking the histogram when you're capturing the flat to make sure that all the peaks are well separated from the left and right hand sides. Also check your camera settings are sensible – for instance if you have been using the stretch in the mini histogram, turn that back to defaults to avoid the stretching of the image distorting your view of what's really going on. It would probably be worthwhile including the control area in any future screenshots if you're still having problems.

Cheers, Robin
captureflat.PNG
captureflat.PNG (779.55 KiB) Viewed 63 times
withflat.PNG
withflat.PNG (769.35 KiB) Viewed 63 times

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