Dear fellow astrophotographers and the ZWO Team,
Kindly seeking a bit of your advice on a strange issue with a brand new ZWO ASI2600MC Duo camera.
Since its first light in March, this camera shows strange (although subtle) diagonal bands on the flat and light frames. Broad bands run across the image at almost perfect 45 degrees: below are an example flat frame and an example light frame as seen in ASIFitsView application. FITS images and the result of PixInsight's FlatContourPlot script are uploaded to OneDrive: link to the files.
I tried to figure out what could be causing this and performed a series of experiments. Found out that the banding did not depend on:
- Light source for the flats
- Camera rotation angle
- Filters
- Devices between the scope (Askar FRA500) and the camera. My regular imaging train is FRA500 -> ZWO CAA (M54 thread to the scope) -> ZWO EFW 5*2" (M54 thread to the CAA) -> Camera tilt plate M54 (bolted to the EFW) -> Camera (bolted to the tilt plate). Removing anything in between the camera and the scope (I leave the tilt plate on, though) does not change the state of things
- Possible light leaks in the imaging train (tried to cover all thread connections with a cloth)
- Exposure time for the flats
- Camera gain setting (although the banding seems to be more pronounced with lower gain values -- but that may be an effect of the image stretch)
- Camera cooling setting or dew heater on/off state
- Power supply. Same thing happens with both mains power and a 12V DC supply
- Suspected gap between the tilt plated and the camera (I have taped out that gap)
There is no such banding on dark frames. Camera window is clean with no sign of oil leaks or smudges. Calibration in PixInsight seems to remove the banding.
I used to have an ASI2600MC Pro before, and I have never encountered such an issue.
Has anyone noticed anything similar? All suggestions are highly appreciated.
Thank you.
Kind regards,
Yuri