Optimum sub frame calculator

Discussion of using SharpCap for Deep Sky Imaging
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Taraobservatory
Posts: 2
Joined: Tue Jun 14, 2022 10:55 am

Optimum sub frame calculator

#1

Post by Taraobservatory »

After scouring the internet I finally found what I have been looking for and it seems to be here :)

I was looking for a tool to calculate optimal exposure for my particular setup and sky. I knew shaprcap could do sensor analysis but I didn't know about the little brain. But here we are. My search is over.

That being said I still have a few questions about compatibility.

1. How well does Sharpcap go with QSI 638? Specifically thinking about the live view function and CCDs here and if its fixed ?
2. How well does the tool work with QHY 268M? Apparently this cam has some special settings with a very high well dept. (What should the settings be?).
3. If I have a SQM meter that measures during imaging session, isn't it better to use the calculator tools.sharpcap.co.uk and get the correct e/pixel/s measured from a dedicated device ?

Kind regards
Roger
Taraobservatory
Posts: 2
Joined: Tue Jun 14, 2022 10:55 am

Re: Optimum sub frame calculator

#2

Post by Taraobservatory »

Anyone ?
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admin
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Re: Optimum sub frame calculator

#3

Post by admin »

Hi,

sorry, this one slipped past me.

For the QSI, firstly you must have an ASCOM driver for the camera, since SharpCap has no direct support. Hopefully such a thing exists and has no major bugs :) Secondly, make sure you put SharpCap into still camera mode when using a large format CCD with slow download times, since live view will most likely lead to problems with poor responsiveness. You can now run most SharpCap tools (including live stacking) in still mode.

Some QHY cameras do have a variety of read modes (for instance High Gain, Photographic, Extended Full Well). SharpCap understands these and the fact that they will have different sensor analysis curves. You will need to run the analysis once for each mode you intend to use (just as you would need to run it once for 8 bit and once for 16 bit mode). SharpCap will keep the data separate and use the appropriate data based on the mode in use (just make sure your SharpCap is up to date for this :) )

Using an SQM and calculating is probably quicker but less accurate - for instance with the SQM you have to trust the manufacturer claims on QE of the device and you are probably somewhat less accurate in measuring the exact area of the sky that you will be working in. Letting SharpCap measure will be more accurate as you are actually measuring the e/pix/s on the sensor, but obviously takes a little time.

cheers,

Robin
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