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Dark Scaling with DSLR - temperature differences
I usually use QHY168C (it is cooled camera so I have never minded dark scaling), but recently I have started building new portable kit with Sony Alpha 5000. I think taking darks every night would be a massive pain, so I am interested in dark scaling, but I don't understand one think - how it deales with different temperatures? I read all exif data of sony raw file and I didn't find any temperature value. Therefore I would apprecieate information how excatly dark scaling works.
It is not required to take darks every session, just do it maybe once or twice a year for a cooled camera (and make one with say 80 or so). Also, a Bad Pixel Map is good to use always as that will work for that sensor at all times. Scaling is not advised, it can be done when the signal is linear, but if there is any other issue like amp-glow, it doesn't scale properly. With a non-cooled camera, I typically make a dark library of a few different temperatures. Since that is quite tricky, I just make a good one every season. When your sensor changes with say 5 oC (or the outside temperature), that would be a nice boundary to decide when to make new ones. It isn't ideal, but that is exactly why cooled camera's were invented.
Thanks! I think I will do so - with about 3 different exposure times every 5 degree.