Hello All,
Thank you for taking the time to view my post.
Last night i ran the sensor analysis function in Sharpcap and it took around an hour to complete and over 2000 frames during the process. However I am confused from the output information and interpreting the values to obtain the optimum settings for my camera.
Does this look right?
If anyone can offer guidance on what i need as my settings I would be most grateful. Please see attached image screen grab of the output data.
Many thanks & Best Regards
Martin
New user and new camera QHY268C sensor analysis
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Martin Farmer
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New user and new camera QHY268C sensor analysis
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- QHY 268C Sensor Result
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admin
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Re: New user and new camera QHY268C sensor analysis
Hi,
it all looks fairly normal apart from the read noise measurements at gains ~70 and above - the area where the read noise rises with increasing gain. That bit looks odd. You can see the read noise results that QHY publish here : https://www.qhyccd.com/wp-content/uploa ... 427827.png - note that there is no increase in those read noise graphs towards high gain.
First thing I would try is another run of the analysis to see if you see the same thing. It shouldn't really take an hour to complete - more typically 3 to 10 minutes. If it is taking a very long time, try using brighter illumination (as bright as it will let you), which encourages the use of shorter exposures during the run. Also make sure you are using the very latest SharpCap 4.0, as I have been improving the sensor analysis code from time to time to make it more robust.
What could cause the high read noise values? Those figures come from two sources
1) measurements of dark frames taken at different gains
2) the relative brightness measurements taken at the end of the process where gain is gradually increased and exposure decreased.
A light leak when capturing dark frames could lead to this sort of thing if it happened for only part of the dark measurement time. Alternatively, if the illumination level changed during the relative brightness measurements, that could also cause this problem.
cheers,
Robin
it all looks fairly normal apart from the read noise measurements at gains ~70 and above - the area where the read noise rises with increasing gain. That bit looks odd. You can see the read noise results that QHY publish here : https://www.qhyccd.com/wp-content/uploa ... 427827.png - note that there is no increase in those read noise graphs towards high gain.
First thing I would try is another run of the analysis to see if you see the same thing. It shouldn't really take an hour to complete - more typically 3 to 10 minutes. If it is taking a very long time, try using brighter illumination (as bright as it will let you), which encourages the use of shorter exposures during the run. Also make sure you are using the very latest SharpCap 4.0, as I have been improving the sensor analysis code from time to time to make it more robust.
What could cause the high read noise values? Those figures come from two sources
1) measurements of dark frames taken at different gains
2) the relative brightness measurements taken at the end of the process where gain is gradually increased and exposure decreased.
A light leak when capturing dark frames could lead to this sort of thing if it happened for only part of the dark measurement time. Alternatively, if the illumination level changed during the relative brightness measurements, that could also cause this problem.
cheers,
Robin
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Martin Farmer
- Posts: 2
- Joined: Wed Jan 05, 2022 11:29 pm
Re: New user and new camera QHY268C sensor analysis
Hello Robin,
Thank you for your reply and advice, I have re-run the test this afternoon please see attachments.
Do you consider this better and the values to use with the camera driver?
Regards
Martin
Thank you for your reply and advice, I have re-run the test this afternoon please see attachments.
Do you consider this better and the values to use with the camera driver?
Regards
Martin
- Attachments
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- Results V2.png (6.87 KiB) Viewed 2553 times
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- Results V2 Text.png (53.81 KiB) Viewed 2553 times
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admin
- Site Admin
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Re: New user and new camera QHY268C sensor analysis
Hi,
those figures look reasonable up to about gain 90 (and since you are incredibly unlikely to use higher gains than that for deep sky imaging, the rest doesn't really matter). However, I can also see that you have changed the camera's read mode to (I think) 'Enhanced Full Well Depth', where the previous analysis was in 'High Gain' (or similar). This model of camera has a number of read modes, and you need a separate analysis run for each, so the new data will not have replaced your early high gain data.
cheers,
Robin
those figures look reasonable up to about gain 90 (and since you are incredibly unlikely to use higher gains than that for deep sky imaging, the rest doesn't really matter). However, I can also see that you have changed the camera's read mode to (I think) 'Enhanced Full Well Depth', where the previous analysis was in 'High Gain' (or similar). This model of camera has a number of read modes, and you need a separate analysis run for each, so the new data will not have replaced your early high gain data.
cheers,
Robin