QHY294MPRO-GAIN OFFSET ISSUE

[lukenash707]

Hi, I have been having some trouble with my QHY294MPRO camera. I tried taking a series of calibration frames last night and also a few nights ago with exactly the same settings. I used a gain of 1600 and an offset of 30 in 16 bit mode and 11MP mode. The first night, I checked the histogram and the the bias frames were in the 1700-1800 ADU range, this seemed really high. For the second night I adjusted the offset and checked some trial bias frames, they came in at 900 ADU. I then ran a sequence of darks frame and the ADU for 300s came out at around 400 ADU which is completely washed out by the bias frame but does seem a bit more logical than the 1700-1800 range. It seems also like when I change the gain in sharpcap, nothing really happens until I hit 3600, then it makes a huge jump. I feel like this camera has given me some good images on some nights but even though the settings stay the same, the next night it performs very differently. I've only had this camera for a few months. Any hints?

[admin]

Hi,

I have the colour version of this camera, and with offset=30, RAW16, 11 megapixel, I get a mean ADU for bias frames (1ms) of about 1920. This varies a little with gain, but not much. Mind you, if I turn the gain up to 3500 then SharpCap reports the camera has disconnected and then closes without warning, so some sort of QHY SDK bug there (this is with the latest SharpCap 4.0 and latest QHY all-in-one drivers).

Anyway, the best bet for you is probably to do some more experiments and note down the gain/offset/exposure/ADU data you measure for bias frames to see if you can spot a pattern of when the values go weird. I have seen issues before with QHY cameras of odd behaviour at minimum exposure, so avoid setting exposure to absolute minimum.

cheers,

Robin

[lukenash707]

Hi Robin, I'm having a strange issue with a loaner camera from QHY (I had to send back my 294M). It says on the side that it's mono camera but sharpcap recorgnizes it as the 294C. Is this a common issue, it seems to be causing a lot of confusion with the processing side of things for me.

Any help on this would be appreciated.

Thanks

[admin]

Hi,

I think we have seen this before. Are your QHY system drivers and version of SharpCap right up to date? I have a feeling that an update of one or the other fixed this for the last person with the problem.

cheers,

Robin