What does Std indicate in histogram (along with max, min,avg)

jbradsh

What does std mean (standard deviation?) in histogram in ASIAIR ? any hints on understanding these numbers and graph more usefully? I presume min is background level, avg is average and the difference is a guide to signal to noise ratio.

Gain I presume is set so the peak of the curve is at least a little away from the left axis - or is Avg minus Min a better guide?

james474789

In very rough terms it can be considered a measure of the noise in the image. If you use the live stack feature you will note the std falls as new subs are integrated. Std should drop by approx 42% with each doubling of frame count.

In terms of setting gain/exposure use tables like these:

https://www.cloudynights.com/topic/573886-sub-exposure-tables-for-asi-1600-and-maybe-qhy163/

dcraid

In my experience Std goes up with more stacking in Live mode. Am I doing something wrong? Might something else be adding noise? Thanks.

AstroDude42

Have a look at Chen‘s answer – he already provided a comprehensive answer to the original question: https://bbs.astronomy-imaging-camera.com/d/13664-histogram-clarification/2

Olli