I'm wondering what offset value other QHY268C owners are using.
Thanks
Thanks
QHY268C offset value
I bought it recently and didn't have time to fully test it, but a friend that also have it suggested the following:
Readout Mode #0 (Photographic Mode) Gain 30 offset 10
Readout Mode #1 (High Gain Mode) Gain 56 offset 15
Readout Mode #0 (Photographic Mode) Gain 30 offset 10
Readout Mode #1 (High Gain Mode) Gain 56 offset 15
You may find this article useful.
https://www.amateurastrophotography.com/qhy268c-test-report
I keep mine at Gain 26 and offset 10. I only use the 268C for broadband OSC and have yet to try the other modes. For narrowband, I use my QHY268M.
Clear skies,
Alex
https://www.amateurastrophotography.com/qhy268c-test-report
I keep mine at Gain 26 and offset 10. I only use the 268C for broadband OSC and have yet to try the other modes. For narrowband, I use my QHY268M.
Clear skies,
Alex
I run a few different settings and here is what I did get:
So I use the same values as suggested by G. Karantzalos
So I use the same values as suggested by G. Karantzalos
Thanks for the suggestions; at the moment I have my gain at 56 and offset at 20 when in high gain mode. In photographic mode I used gain 26 and tried offset of 10. I've got some experimenting to do!
Knox W
Knox W
Well Written
There is a nice article about the relation of gain and offet and especially how to measure the required offset for a given gain, which is easy to do, see
https://daleghent.com/2020/08/understanding-camera-offset.
CS
Gernot
https://daleghent.com/2020/08/understanding-camera-offset.
CS
Gernot
Thanks, good article.
Knox W
Knox W
When using in photographic mode with my F4 Newton I use gain 0 with an offset of 30 for broadband data. When using with a narrowband filter like the L-Exreme is use gain 30 with an offset of 45.
i came to my conclusions on using these setting values based on a combination of using the graphs in the camera documentation & also doing sensor analysis through sharpcap. Regardless of what the documentation says, I strongly recommend doing your own analysis in sharpcap, particularly to find a good offset value.
What I’m doing above works quite well for me.
i came to my conclusions on using these setting values based on a combination of using the graphs in the camera documentation & also doing sensor analysis through sharpcap. Regardless of what the documentation says, I strongly recommend doing your own analysis in sharpcap, particularly to find a good offset value.
What I’m doing above works quite well for me.
Helpful Concise
I would recommend picking one offset value and sticking with it. It really doesn't make too much difference overall and might end up being a serious pain when, in the future, you need to process multiple images with all kinds of offsets picked without understanding what offset really is (as probably majority of users don't know).
Well Written Insightful Respectful Concise
I would recommend picking one offset value and sticking with it. It really doesn't make too much difference overall and might end up being a serious pain when, in the future, you need to process multiple images with all kinds of offsets picked without understanding what offset really is (as probably majority of users don't know).
not sure if you mean that sticking with the same offset per specific gain setting? If so I agree with you.
If you mean sticking with a “one size fits all” offset value across varying gain setting values, I do not agree in that case. a different offset is usually needed at different gain settings & when using different photographic modes with this camera. Testing kind of proved this out for me.
I would recommend picking one offset value and sticking with it. It really doesn't make too much difference overall and might end up being a serious pain when, in the future, you need to process multiple images with all kinds of offsets picked without understanding what offset really is (as probably majority of users don't know).
not sure if you mean that sticking with the same offset per specific gain setting? If so I agree with you.
If you mean sticking with a “one size fits all” offset value across varying gain setting values, I do not agree in that case. a different offset is usually needed at different gain settings & when using different photographic modes with this camera. Testing kind of proved this out for me.
This is one of those situations where fussing around gives miniscule benefit while being technically right (and from what I see I can expect you to defend your approach vigorously just on that technicality).
Thanks for all the suggestions. Rob Kiefer's chart was quite helpful.
I used ASI Studio to study histograms of the bias and darks I took at various modes, gains and offsets.
I will probably only use the High Gain mode when I use my L-Extreme filter; all other shots will most likely be take in photographic mode, gain 0 or 26.
I used mode 0, gain 26, offset 20 (UV/IR filter) for images two nights ago of IC 447 and I'm quite pleased with the results.
IC 447, converted to jpeg and resized for my very slow internet here (HughesNet). Processed in PixInsight.
Thanks again,
Knox W
I used ASI Studio to study histograms of the bias and darks I took at various modes, gains and offsets.
I will probably only use the High Gain mode when I use my L-Extreme filter; all other shots will most likely be take in photographic mode, gain 0 or 26.
I used mode 0, gain 26, offset 20 (UV/IR filter) for images two nights ago of IC 447 and I'm quite pleased with the results.
IC 447, converted to jpeg and resized for my very slow internet here (HughesNet). Processed in PixInsight.
Thanks again,
Knox W
Helpful Respectful
I would recommend picking one offset value and sticking with it. It really doesn't make too much difference overall and might end up being a serious pain when, in the future, you need to process multiple images with all kinds of offsets picked without understanding what offset really is (as probably majority of users don't know).
not sure if you mean that sticking with the same offset per specific gain setting? If so I agree with you.
If you mean sticking with a “one size fits all” offset value across varying gain setting values, I do not agree in that case. a different offset is usually needed at different gain settings & when using different photographic modes with this camera. Testing kind of proved this out for me.
This is one of those situations where fussing around gives miniscule benefit while being technically right (and from what I see I can expect you to defend your approach vigorously just on that technicality).
Best not to make assumptions about what how I will or will not respond. I agree that the potential benefit of fiddling with the offset beyond a point won't produce great or probably even noticeable benefit as long as you're in the right ballpark. In my case though fine tuning was a simple case of experimenting with some different settings with the camera on a light panel while watching the histogram. It only took a few minutes & I had it all set up to the sharpcap sensor analysis at that point anyway. I spent the money on the camera, might as well take some extra time to try to dial in the offset in a place that’s based on experience with that specific unit & not a guess.