Clarification of Sharpcap/ZWO gain units

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Eyeroll1952
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Joined: Tue May 25, 2021 2:03 pm

Clarification of Sharpcap/ZWO gain units

#1

Post by Eyeroll1952 »

I am a bit confused about the relationship between gain units set in Sharpcap and those presented by ZWO and probably other manufacturers, i.e. the 0.1 dB units. I assume that Sharpcap units sent to the camera are linear - is this correct? If so, a ZWO gain of e.g. 200 means 20 dB, but is this in power units or in amplitude units? That is, in linear terms does a ZWO gain of 200 * 0.1 dB correspond to a linear (Sharpcap) gain of 10 or 100? Perhaps a simplified version of the question is this: if I want a "200 units of ZWO gain", what do I put into the gain setting in Sharpcap?

Thanks!

Paul
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Re: Clarification of Sharpcap/ZWO gain units

#2

Post by admin »

Hi Paul,

simple answer... 200. SharpCap does not adjust the gain units for ZWO cameras between the UI values and the camera. Additionally, setting gain=200 on a ZWO camera will get a 10x brightness increase over setting gain=0.

Lots of other brands of cameras use this 0.1dB scaling, but some use 1dB (Moravian instruments, some QHY), while others have a multiplicative gain where the amount of gain is the value entered divided by the minimum value (Altair). Finally, some are just numbers with no real pattern except that bigger numbers mean brighter (lots of modern QHY cameras, sadly).

I did mean to add a tooltip to the gain that shows more info - must get around to doing that.

cheers,

Robin
Eyeroll1952
Posts: 11
Joined: Tue May 25, 2021 2:03 pm

Re: Clarification of Sharpcap/ZWO gain units

#3

Post by Eyeroll1952 »

Hi Robin, thanks for clarifying!

Paul
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