Use a pedestal if necessary for NB

Gregory Funderburk

Enjoyed your newest release "Use a pedestal if necessary for NB", thank you.

Quick question, does this relate to offset? I have a couple of the new QHY600 cameras and they advise to set the correct gain and offset by looking at the histogram and making sure none of it touches the left and to change (increase or decrease) offset to move it further to the right if touching the left or if to far to the right then reduce offset.

I am guessing that if I took several nights images with the wrong offset your new  "Use a pedestal if necessary for NB" would correct any problems.

Am I correct in my thinking?

Thank you

BlockHead

My gut says... the offset you apply to your sensor will be in both the darks and the lights. So when you subtract this is subtracted as well and you end up with the same issue as before. The problem really is the sky is so dark in NB filters... you can get negative values during calibration...so adding back a value before outputting the result fixes that.  I may not be understanding everything and could be wrong... I will clarify if so.

With regards to the offset mismatches and how to fix... this I definitely do not know. My gut says the offset is coupled with the gain setting- so no I don't think you can do that..but again..I am probably wrong.I do know...you really need to pick a setting and stick with it throughout...or calibration will not work!

-the Blockhead