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Old 24-10-2017, 05:40 AM
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Astrofriend (Lars)
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Camera simultions in Excel

When boring times comes it could be both fun and interesting to do some calculations. This time I did an Excel sheet over the four cameras: Atik 16200, Canon EOS 6D, ZWO ASI1600, QHY367C and a perfect camera that only exist in my mind. I have the Canon 6D and wanted to see how time efficient it is compare to the others.

In the Excel sheet it's possible to setup data for the cameras and object information, light pollution, thermal noise, readout noise and max level that shouldn't saturate (clipp). At the end you see how many sub images it takes to reach a given S/N, Signal / Noise ratio. It also calculate the total exposure time included dead time between images.

Take a look here where I have wrote it down if you find it interesting:

It's very simple so don't expect it to be perfect but you can have a lot of interesting information from it if you test with different parameters.

You can download the Excel sheet if you find it interesting and test your own numbers.


Last edited by Astrofriend; 02-11-2017 at 08:59 PM.
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Old 25-10-2017, 03:20 PM
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RickS (Rick)
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Hi Lars,

I think it's very worthwhile to do the calculations and understand what's happening under the hood.

I have a somewhat simpler model that I use for evaluating the overall performance of different scope/camera combinations.

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Old 25-10-2017, 03:46 PM
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billdan (Bill)
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Hi Lars,

I haven't digested it all yet but a scan of the data reveals you have the bias set way too high.

For most 16 bit CCD's we set the bias to 750 (500 - 1000 rec) which maps down to 47 for 12 bit cameras. In fact I believe ZWO are going to fix the bias at 50 on new 1600 models. Yet you guessed at 2048 bias and 1024 for the ZWO which is too high and will stuff up your calc's.

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Old 02-11-2017, 09:11 PM
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Astrofriend (Lars)
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Thanks for the information.

I was only sure about my the Canon's bias, it's fixed to 2048 ADU, ASI1600's bias is adjusable if I understand it correct. The bias are stored in the red fields that you set yourself. But I changed it to 512 and 128 and will come up when I upload a new version later.

Lower bias give better dynamic range but it could not be too low, then it clip the neg noise levels.

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camera, exposure, simulation

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