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Question on Sharpcap Darks

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#1 unimatrix0

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Posted 26 July 2021 - 01:27 PM

I have taken dark frames before of course, but with cameras of plenty of amp glow I don't seem to be able to calibrate the glow out completely, or the darks over compensate during live stacking and I see a purplish /brownish outline of the amp glow on the right. 

How do you guy take the darks?  

How many darks do you usually take?   I have tried 10, 20, 30, I'm not sure what's the magic number or if there is any benefit taking even more? 

 

I assume you know already what exposure and gain you gonna use or already have an extensive library of darks for all combos of exposure+gain+offset? 

 

I also try using just the flat with the dark flat combination in sharpcap, but that won't help with amp glow. 



#2 GaryShaw

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Posted 26 July 2021 - 02:15 PM

I take them using Sharpcap's 'Capture Darks' process. My ASI294 mc is prone to amp glow and the SC process always eliminates amp glow and hot pixels.


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#3 alphatripleplus

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Posted 26 July 2021 - 04:28 PM

I take darks at the same gain, exposure and temperature settings as my lights and use at least 15 darks to create a master dark. DId you make sure that the temperature for your master dark matches the temperature of your lights (to within at most a few degrees)? If you have a temperature mismatch, that might show in residual amp glow even if you match exposure and gain.



#4 Clouzot

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Posted 27 July 2021 - 07:29 AM

I take darks at the same gain, exposure and temperature settings as my lights and use at least 15 darks to create a master dark. DId you make sure that the temperature for your master dark matches the temperature of your lights (to within at most a few degrees)? If you have a temperature mismatch, that might show in residual amp glow even if you match exposure and gain.

In addition to what Errol suggests, also make sure the brightness/offset camera setting is the same as for your lights. That's one thing that may give overcorrecting darks. That setting may have been changed by, say, the famous Sharpcap "Brain"...


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#5 alphatripleplus

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Posted 27 July 2021 - 07:38 AM

Yes, Clouzot makes a good point on using the same brightness/offset setting.(One other mistake I have almost made is trying to use a dark with different binning from a light,  e.g. 2x2 vs 1x1, but most EAA software won't let you subtract different binned darks from lights.)




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