Time efficiency simulations of three cameras

[Astrofriend]

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 three cameras: Atik 16200, Canon EOS 6D and ZWO ASI1600. 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 and 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 and dead time between images. It only compare pixel to pixel, not that the sensor area or the pixel size is different.

Take a look here where I have wrote it down if you find it interesting:
http://astrofriend.eu/astronomy/tutorials/tutorial-camera-time-efficiency/tutorial-camera-time-efficiency.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.

/Lars

[Astrofriend]

I did an update and included the dark current noise.

It could be interesting to compare the uncooled DSLR camera at different temperatures.

I'm lucky to live in a cold country with about zero degrees temperature or lower when doing astrophotographing. But if you have about +10 degrees Celcius or more then the thermal noise can be heavy.

http://www.astrofriend.eu/astronomy/tutorials/tutorial-camera-time-efficiency/tutorial-camera-time-efficiency.html

See at bottom, do a test with different values and see what you get.

Note:
This are not any precise calculation but give you an overview what happens under different circumstances!

/Lars

[Adam J]

hi, perhaps you could give a quick summery of the overall findings?

[Astrofriend]

Hi,

Because I don't have all data and it's a bit simpliefied in the calculations you shoud not use this to which camera to buy. If you have more correct data for a particular camera you can overwrite the data in green fields. All cameras are very good. It's more about how to use the camera.

If you want to take many short expousures to frezze the seeing you should not have a mechanical shutter.

If you have a hot outdoor temperature a uncooled dslr is not the first choise.

 

What's very interesting to see is, if I shorten the exposure, how many more subimages do I need to reach the same S/N for that camera. Or how short exposure must it be to not oversaturate bright objects. How does the iso/gain setting influence the time it takes to reach a given S/N. How does the temperature setting change the S/N, Etc

Just test with different input data (red field) and see what you get. That's the main purpose of this excel.

 

And take a look at my homepage if I have done any update of the file since last time.

Lars

[London_David]

The spreadsheet sounds really interesting. I started putting together exactly the same thing for myself a few months ago but I could never quite get the maths right — plus I never use excel for more than a simple table so I was trying to figure that out too. I abandoned it to other things in the end.

I’d love to check out your version but the link on your site gives me a 404 at the moment — can you repost. Thanks!

 

[Jessun]

Tjena! (=Howdie or Hiya)

Cool idea. I don't quite follow step 8 as defined by pixels, and how that translates to absolute FOV when let's say using the cameras in the same scope.

I for one struggled somewhat with the 460Ms to cover much, so as I looked at the 16200, I gave full credit to the larger sensors FOV to compare mosaic time and thus 'speed' of the combos.

/Jesper

 

 

[Astrofriend]

Hi Jesper,

All telescopes are thought to have focallength that give 1" / pix, see row 18. Then more pixels cover more fov and then less number of images to cover a 100 millions pixels fov, see row 24.

It's the same as if had been calculated to cover a degree x degree fov, but it was in this case better to use pixels as a calculation base.

I hope you find some use of it.

 

You live in Frence but speak Swedish?

/Lars