ASI1600mm gain settings vs total integration time

[mos]

Hi everyone, 

I can't seem to find the answer for this, but I'd like to know whether a final integrated stack of a given total integration time is any different depending on the gain value used. 
i.e would 100 images at gain 0 yield the same SNR etc as 50 images at gain 139 for instance (or whatever gain may be the appropriate 1:1  direct comparison)?  

I'm thinking of trying out gain 0 as I have reasonably dark skies. I know gain is an effective way to reduce exposure time, but does it have an effect on total integration time required? 

 

Thanks, 

Matt

[wimvb]

As far as I know it isn't, but the math behind it isn't straight forward, because the quality of the final image is not only determined by single sub exposure time, gain, and number of subs.

At low gain, a CMOS camera has a higher dynamic range than at high gain. When you stack multiple images that have low dynamic range, you increase the dynamic range again. The advantage of high gain is that you can use shorter single sub exposures. During stacking you can then exclude images that have star trails, satellite trails, passing clouds, etc. Also if you use short enough exposures, you may get away with not guiding.

Generally the better astrophotographs have long and similar total integration times, regardless of which gain setting and sub exposure time was used.

ZWO wrote this in their blog:

https://astronomy-imaging-camera.com/tutorials/cooled-asi-camera-setting-in-ascom-driver.html

I do most of my imaging at low gain, below unity, and 120 - 240 seconds (the shorter time for L, the longer time for RGB). My camera has a somewhat high read noise (compared to other ZWO cameras), and I like to image at high dynamic range.