Odd behavior with my QHY10

[XCalRocketMan]

OK, here's a good one for you guys and gals out there in AP land.

For a few years I had used a QHY10 as my only astro camera. It is OSC and made for an easier learning curve. Then, about 2 years ago I purchased a ASI1600mm Pro which is now my main stay for AP. But for comets I still use the QHY10 since it is much easier to take the required subs and not have to deal with filters and the hectic post-processing to follow. This December 23rd I imaged comet C/2017 T2, and I have finally gotten around to processing the images. I took 60 120sec subs. I processed them using the BPP script in PixInsight - using MasterDark, MasterBias and new flats. I ran with calibrate only as I was going to register on the comet head.

What I got from the BPP was a set of almost totally blank images (a few bright white stars, but no comet, and jet black background). Yikes! What happened. I checked everything and ran the BPP again. Same result. So I decided to check out the individual subs to see if anything stood out as odd.

The lights looked OK; lots of stars, a greyish background from the LP and the comet (with a tail!). The MASTER BIAS and MASTER DARK looked about right too - until I checked the statistics of each image. The Mean ADU of the MASTER BIAS was 566. Sounded a bit high, but OK, I'll go for it right now. The MASTER DARK's ADU was 620. Then I checked the lights - an ADU of 413! That's right, lower than a BIAS or DARK. How the heck can that happen??? So it seems when the calibration step starts to subtract the BIAS and DARKS I would get a black result.

This is nuts. What am I missing here? Camera error? Software error? Anyone care to take a stab at this?

[Baskevo]

I'm pretty new to the technical side of things, but the only thing I have seen change the ADU values are 1) using the wrong bit depth, and 2) using different settings under the format explorer. For example, if I analyze the image statistics at 8-bit instead of 16-bit, I get much lower numbers. Furthermore, with my DSLR and under the RAW settings, if I changed from 'demosaiced RGB' to 'Pure Raw', my ADU values would be different.

I have never seen these 2 cases affect the final image though. Wish I could be more help Maybe try a different program for reading ADU to see if you get the same results?

[XCalRocketMan]

I'm pretty new to the technical side of things, but the only thing I have seen change the ADU values are 1) using the wrong bit depth, and 2) using different settings under the format explorer. For example, if I analyze the image statistics at 8-bit instead of 16-bit, I get much lower numbers. Furthermore, with my DSLR and under the RAW settings, if I changed from 'demosaiced RGB' to 'Pure Raw', my ADU values would be different.

I have never seen these 2 cases affect the final image though. Wish I could be more help Maybe try a different program for reading ADU to see if you get the same results?

Tried Nebulosity too - same values. This is really odd.