QHY8 Pro Frustrations

[Roy@Aldermaston]

I would welcome advice from anyone who has experience of the QHY8 Pro camera. I bought it as a step up from my modded Canon 1100D, but aside from the advantage of step-point cooling it's proving to be an expensive disappointment. Compared to the Canon, the images lack contrast and overall it seems far less sensitive. I've spent hours of wasted imaging time trying to get the right balance between gain and offset, using both the manufacturer's instructions and the many contradictory methods posted online. None seem to produce any significant improvement.

I'm beginning to despair of ever getting reasonable results, so if there is anyone who uses this camera and is satisfied with the images that it produces I'd be more than grateful to hear from them, and would welcome any tips for setting the gain and offset.

Excuse the rant, 

Roy

[Daniel-K]

have you got a image to show us what you have been able to get so far?

[Spikey]

I've got an older QHY8, can't remember the settings off the top of my head but I can check mine if you like.

[r3i]

I use a gain of 1 and offset of 117 with my QHY8.

[sloz1664]

Hi Roy,

I've a QHY8 pro and if you are saying it's far less sensitive, you have something very wrong.

To get you going try gain 8, offset 120. That's my standard settings.

If you read the manual there is a procedure for setting your gain & offset. You must really

try to set your gain & offset, as all cameras differ especially if you have any LP filters attached.  

I run my QHY8 pro at -20 C with exposures up to 20 mins and had no problems, apart from my own doing.

I use MaximDL for imaging, guiding, stacking & colour conversion.

cheers

Steve

[Roy@Aldermaston]

Thanks for the replies.  I've attached a zipped stack of 11 600 sec lights taken with gain at 15 and offset at 125.  There is a strange circular banding effect around the image centre when its stretched, perhaps  caused by having the gain set too high, its certainly produced spectacular vignetting.  

Roy     

NGC7142.zip

[Roy@Aldermaston]

Thanks Steve, I'm relieved that it's probably me and not the camera.  When setting the gain and offset should I have my LP filter and MPCC fitted as usual, and does the camera need to be fitted to the scope, or just free standing.  

Roy

[Spikey]

Mine are set to 7 & 120.

[Spikey]

Thanks Steve, I'm relieved that it's probably me and not the camera.  When setting the gain and offset should I have my LP filter and MPCC fitted as usual, and does the camera need to be fitted to the scope, or just free standing.  

 

Roy

I understand that the gain & offset are set at the driver and operate independently of your peripherals; so you don't need the camera attached to anything in the imaging train to make the adjustments other than the device interfacing with the camera.

[Roy@Aldermaston]

Thanks Simon,

I've had another go and worked through the sets given in the manual.  The values that I've come up with are Gain = 3  and Offset = 120, and that seems to agree with those that others are using.  Now all I need is a clear sky and no wind.

Roy

[Spikey]

Now all I need is a clear sky and no wind.

 

Roy

If you get any send some over to the peak star party this weekend I have a feeling we may need it

[sloz1664]

Hi Roy,

Glad you have re-set your gain & offset. As Simon states you only need to connect your camera to your imaging software of your choice.

Yes you need to attach any LP filters you use with your camera. I have checked your tif image and after stretching can see the circular banding you mentioned.

Yours stars in the corners are very eggy have you got your spacing correct. Also, have you removed any vignetting in your image.

If you can give me your image scale (arcsec/pixel) I can check you image curvature.

cheers

Steve

[Roy@Aldermaston]

Thanks Steve,

The spacing was set up by Bern at Modern Astronomy and checks out OK, and apart from cropping to remove the over-scan the image hasn't been processed.   I never had that banding before, but its appearance does correspond with with the adjustment of gain and offset to higher values.  Once the weather clears I'll experiment with the new settings before tackling the curvature issue.  

Roy