#1  
Old 24-10-2017, 06:40 AM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 184
Camera simultions in Excel

Hi,
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:
http://astrofriend.eu/astronomy/tuto...fficiency.html

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.

/Lars

Last edited by Astrofriend; 02-11-2017 at 09:59 PM.
Reply With Quote
  #2  
Old 25-10-2017, 04:20 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,581
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.

Cheers,
Rick.
Reply With Quote
  #3  
Old 25-10-2017, 04:46 PM
billdan's Avatar
billdan (Bill)
Registered User

billdan is offline
 
Join Date: Mar 2012
Location: Narangba, SE QLD
Posts: 1,228
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.

Cheers
Bill
Reply With Quote
  #4  
Old 02-11-2017, 10:11 PM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 184
Hi,
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.

/Lars
Reply With Quote
Reply

Bookmarks

Tags
camera, exposure, simulation

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 02:37 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Lunatico Astronomical
Advertisement
Meade Australia
Advertisement
Bintel
Advertisement
OzScopes Authorised Dealer
Advertisement
NexDome Observatories
Advertisement
SkyWatcher Australia
Advertisement
Celestron Australia
Advertisement
Astronomy and Electronics Centre
Advertisement