hello!
on CFV16 + 500cm:
I am experimenting these vertical lines in low light, they show when I raise shadows in Lightroom, anybody experimented this before ? is that a normal issue with CFV16 ?
thanks!
https://lh6.googleusercontent.com/-...02eBWx3Dw/s993-no/2014_Mars+%287+of+74%29.jpg
https://lh3.googleusercontent.com/-...H_VnB8Mx8/s993-no/2014_Mars+%288+of+74%29.jpg
Did you rotate the first image by a few degrees in Lightroom? I ask because the banding is not vertical, whereas it seems to be exactly vertical in the second image.
I have the same sensor in a different back, but I have never seen anything like that degree of banding. If I take what is effectively a bias frame (camera at fastest shutter speed, lens capped, smallest aperture or darkened room just to be sure no light gets in), shot at ISO 400, and push it to the equivalent of ISO 1600, only then do I start to see very subtle, broken wavey bands. I've seen this behaviour before in several CCDs, including highly tuned astronomical CCDs. It disappears though if I set the back to subtract a dark frame of equal time, which tells me that the subtle pattern is repeatable. That's the key thing - being repeatable means that it can be cancelled out.
Could you take a couple of bias frames, separated in time, and show them here? That would remove the variable of external light and we could see what the readout process alone is doing, and how repeatable the pattern is. Subtracting an internal dark frame would be another key test, but I don't believe your CFV16 back can do that?
Ray
