QHY vs. ZWO Drivers for 183M Sensor Cameras

Sequence Generator Equipment Compatibility
21

Ben - I’m using a QHY183M and a QHY247C.
In both cases I sat down with SGP and took short dark frames at different gain settings and upped the offset until the minimum value in the statistics panel started to come off its lowest value, ending up typically in the range 50-200. Remembering that you need unique calibration files for each setting, I decided on low, medium and high values, which are favorable to stars, galaxies and nebula respectively.
My lowest gain setting would be zero and then one where the read noise about halves and then halves again. In the case of the QHY183, it was 0, 5 and 10. I may bin the 183 with longer focal lengths so I repeated with 2x2 binning and using the same gains, required different (lower) offsets.

I had to go into the camera settings tab in SGP sequencer window to alter the values. In future, with the latest ASCOM 6.5 platform supporting ASCOM properties for gains and offset, it may be possible for Ken and Jared to make it a sequence setting option.

22

Thanks for the suggestion, buzz. I did a little bit of dark testing with my QHY183M with offset but have not done too much with the gain yet. I suspect my galaxy imaging could stand for higher gain than I’m using now at the expense of saturating more of the stars.

Ultimately, this is best determined by figuring out optimum exposure using the read noise and flux of the features of interest. And the read noise with these cameras, of course, is variable with the gain.

Being able to programmatically change gain and offset in a sequence would be a welcome addition to SGP!

Ben

23

I typically do my sequences in two bites. The first captures the stars, with low gain. The second goes after the fainter stuff, with high gain. I combine the two in the image processing.