Optimal Exposure and Noise Calculator

[Jens Scheidtmann]

Hi Joseph,

Am So., 5. März 2023 um 06:07 Uhr schrieb joseph.mcgee at sbcglobal.net <
joseph.mcgee at sbcglobal.net>:

> [...]
> You raised a suggestion that bias frames could be used to determine
> sensor read noise.  I must be missing some knowledge in this area. I
> just ran a test with my planetary camera (ASI-178), where I captured a
> set of bias frames incrementing the gain from 0 to 400 in steps of 50,
> with an exposure time 32us, (I believe that is the lower limit for the
> ASI-178).  I then used a tool that can assess noise in the image.  The
> noise measured in each image increased as the gain increased; so this
> did not match the downward trend I expected from the ZWO read-noise graph.
>
>
Bias frames capture the read-out noise of the electronics in ADUs
(analog/digital converter units). When you're changing the gain, you're
also changing the ADU~electron relationship. Manufactureres also have a
graph for that. You at least have to use the respective chart to convert
that reading to e-rms.

Jens
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