QHY294MPro issues - help needed.


QHY294MPro issues - help needed.
« on: February 05, 2021, 10:32:16 AM »
I have 4 other QHY cameras and they work fine. This one is giving me real problems and I have reached the end of the road. Apart from the non-operation over USB3, or through my Paramount hub, or the unreliable USB connection success in general, the random horizontal stripes and the ASCOM driver locking the camera if you view or make changes to the properties - I have reached what seems to be a dead-end.

I cannot flat frame it to save my life. I am imaging SH2-224 in Ha. 900-second exposures in 11MP mode, gain 1750, offset 5. Win 10 Pro 64-bit, SGP acquisition. I imaged one night and without changing anything, went on to do flat frames and dark frames the following day. I calibrated the images in PixInsight. I did not use a script but did it manually, calibrating flat frames with darkflats only before integration and image frames with matching master dark frames and master flats. All calibration and image exposures were done at -15C. 
I repeated the operation (and calibration exposures) several times, with the same result.  The DropBox below has master flat, master dark, calibrated frame and calibrated stack, along with screen grab of ASCOM driver.

I cannot remove the light and dark vertical bands running down the sides of the lights. If you look carefully, the position of these is different in the lights and flats. The camera has changed its characteristics between operations - yet I have not done anything other than turn it off and on again between lights and calibration exposures.

I am really struggling with this and need urgent help from QHY. I'm writing my fourth book on astrophotography and really need this camera to be working. I have checked and double-checked everything.
The ticket system is not working but it is very likely that this camera is broken, the design has inherent problems, or the firmware/driver/ASCOM are corrupting operational settings somehow.

« Last Edit: February 05, 2021, 10:38:58 AM by buzz »
Chris Woodhouse FRAS


Re: QHY294MPro issues - help needed.
« Reply #1 on: February 07, 2021, 03:50:26 AM »
Could you please send all the original files in fits?  It's a little hard for us to operate your file.
If it's too big, you can use https://wetransfer.com/  send to my@qhyccd.com
Also, you can compress before you do the transfer.


Re: QHY294MPro issues - help needed.
« Reply #2 on: February 07, 2021, 04:36:53 AM »
Dear ma-rs

I have converted the files to fits, compressed and sent them over using wetransfer.
I have also included another master flat file, made with a neutral density filter over the telescope and using longer exposure times (15 s rather than 1 s).  If you look at the two master flats, the width of the dark margins in entirely different. It looks like this camera has a different gain variation with different exposure duration. Using the longer master flats is better matched to the image, but it is still not good enough for narrowband imaging.
Chris Woodhouse FRAS


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Re: QHY294MPro issues - help needed.
« Reply #3 on: February 07, 2021, 10:34:23 PM »

I have received the image you sent. In flat, the image caused by light leakage cannot reach the bright center and dark edges. Can you check the edge seal of this system? Or help me take photos from the camera to the connection end of the telescope.
In addition, does this abnormal flat only appear in the Ha channel? Have you tried other filter channels? Have you had similar problems.


Re: QHY294MPro issues - help needed.
« Reply #4 on: February 12, 2021, 11:47:34 AM »
Hi - I have been asked to return the camera by QHY so I cannot take images of the setup.
For information, however, the shading at the sides occur with all filters (LRGBSHO) and the camera is bolted to the CFW3 with the special slim adaptor. I am using 36 mm filters, so there is plenty of clearance. This is a refractor design, with a moonlight focuser, all screw-coupled. The 'flat' is an A3 electroluminescent panel with a diffuser set 30 cm from the end of the refractor. Looking down the refractor, there are no obstructions to the light reaching the sensor.
There are no light leaks either. I already tested by taking a 600s dark frame, with the lights on and the lens cap on. All frames were taken 5 minutes or more after the camera reached its operating temperature.

Out of interest, I am not alone - another user has seen exactly the same pattern on his camera, which is also being replaced. I have seen other flats from this camera that do not show this issue at all, so there is clearly variability of some kind.
Chris Woodhouse FRAS


Re: QHY294MPro issues - help needed.
« Reply #5 on: March 17, 2021, 01:49:45 PM »
I would like to say thank you for the quick turnaround of my 294MPro.  The returned camera, and the latest ASCOM drivers have fixed the following:

USB3 connection issues and connectivity in general
ASCOM 6.5 compatibility
64-bit Application compatibility
Image striping

I need to update this thread - my remaining issue, concerning dark bands down either side of the sensor, which changed with filter and target, has been resolved. It was not a fault of the camera. I still don't know why but I have solved it.

I was using 36mm Optolong filters in a QHY filterwheel. All my images with LRGBSHO filters showed a degree of darkening down both sides, which were different between the images and the flats. I could not calibrate it out.

In pure desperation, I swapped the 36-mm Optolongs for 32 mm Astrodon filters, from another QHY wheel. The problem entirely disappeared. I am not exactly sure why - but I noticed that the Optolong filters coatings did not go the edges and when I compared comparable filters efficiencies, all of the Optolongs were worse (some considerably) than the Astrodons.
« Last Edit: April 02, 2021, 03:57:01 AM by buzz »
Chris Woodhouse FRAS