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Sky Background Calculator and Quantum Efficiency

Posted: Mon Mar 30, 2020 10:39 am
by Topographic
Hi

I am using the ZWO ASI 183MC Pro, the only figure I have for QE is 84% (mono sensor). Do I enter this and then select the colour button?

Thanks

David

Re: Sky Background Calculator and Quantum Efficiency

Posted: Mon Mar 30, 2020 6:25 pm
by admin
Hi,

Yes, by selecting the colour option you're effectively allowing for the fact that each colour filter lets through a bit less than one third of the light available. The underlying QE is unchanged, although you do have to remember that the 84% value as a peak value at a particular wavelength and the average across the whole of the visible spectrum will be smaller.

Cheers, Robin

Re: Sky Background Calculator and Quantum Efficiency

Posted: Mon Mar 30, 2020 6:41 pm
by Topographic
Robin

I assumed a lower than 'peak' efficiency (-10%).

thanks

Daid

Re: Sky Background Calculator and Quantum Efficiency

Posted: Thu May 21, 2020 2:12 am
by stephen2615
Hi Robin,

I was wondering about what impact the moon has on the sky background calculator. Surely a full moon would have a significant impact on the calculations. I have a cousin who lives in a the darkest skies area I know and I try to take advantage of this location compared to my Bortle 5 skies. The full moon completely changes what I can see so this suggest the calculator should be adjusted for the moon.

regards

Stephen

Re: Sky Background Calculator and Quantum Efficiency

Posted: Thu May 21, 2020 6:37 pm
by admin
Hi,

Yes, definitely. The full moon in the sky near to the target that you are trying to image is equivalent to some pretty significant light pollution. The online calculator really only give some guidance – to do this properly it's best to use the smart histogram functionality in SharpCap to actually measure the background brightness level.

Cheers, Robin

Re: Sky Background Calculator and Quantum Efficiency

Posted: Sat May 23, 2020 1:48 am
by stephen2615
Hi Robin

Thanks for the response.

I will have a look at the smart histogram functionality. I have so much going on in setting up the process I almost need a checklist. I am trying to get a good spreadsheet together to give me ideal exposure times.

Regards

Stephen