Dark frame is completely dark on SV605cc

[oopfan]

So this means I was right? Oh, happy days!

Brian

[admin]

I have few questions:
1 - Have I done right by using same Black level for Darks and Stacking?
2 - Have I done right when using Darks made through 500msec exposures' for Stacking 5sec. exposures?
3 - And last but not least - I am having difficult time to understand why Black level should be higher, in my logic it's like pixels below it will be considered black, and by putting it to a high number I also reduced the dynamic range. Please help me understand.

Ehud.

Hi Ehud,

Q1 - yes, the right thing to do is to use the same black level for both
Q2 - no, you should use the same exposure length for both, not different exposure lengths (same gain 2)
Q3 - Depending on the gain, there is some randomness in the pixel values coming from the camera (more randomness for higher gains). The black level control adjusts the average pixel value produced by a pixel with no signal. Sometimes pixels with no signal will have a bit higher value, sometimes a bit lower. You adjust the black level so that the pixel value from a dark pixel (even including the randomness) is always above zero. Otherwise you introduce a bias into the data for pixels that would have a value below zero, but can't since the minimum value is zero.

cheers,

Robin

[Ehud]

Robin,
Thanks for the explanations! and...
You are always right (and even if it's a true bug - you will handle it) - the issue is on us (if needed; with your help) to provide you the right data to analyze the issue