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QHY600 Background noise

QHYCCD QHY600PH M CMOS Dark Frames
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sjunge avatar
sjunge avatar
Hello together,

I have the impression that my QHY600M has problems with background noise and I am in discussion with my dealer. The camera is second hand and was at the dealer for repair a week ago. After testing it, I notice a background noise even at lower temperatures that I have never seen before. The dealer insists that the noise profile is normal, but I have concerns. The profile shows noise as high as 50k ADU at 0C and 240s. Also at -10C the noise is remarkable hight. Bias images look normal and as expected.
Could someone be kind enough to provide me with some sample images for bias and dark and a uncalibrated light 1x1 and 2x2 for comparison? That would be great.


Thanks

Sven
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John Sikora avatar
John Sikora avatar
Any particular gain? I've got 1x1 but not 2x2.
Philippe Oros avatar
Philippe Oros avatar
Hi Sven
I was also very surprised at the beginning when I started using the QHY600 !
This phenomena is known with that cam and it can be corrected 100% with cosmetic correction during integration in Pixinsight 
If you choose carefully your meds, gain and offset according to the QHYCCD documentation you can have very good results
CS
Philippe
Mark avatar
Mark avatar
I also see lots of warm pixels and had a noisy bias. Cosmetic correction and dithering clears the impact of the warm pixels and finding the right USB traffic setting fixed the bias noise issue. Both things were a major concern initially - but now dealt with.
Helpful Supportive
Kevin Morefield avatar
Kevin Morefield avatar
Sven,

Could you post a link to one of your bias or dark subs?

Thanks,

Kevin
Peter Bresler avatar
Peter Bresler avatar
You might contact QHY support [email]cha@qhyccd.com[/email]

He also will want a dark frame. Use Dropbox.

Peter
John Hayes avatar
John Hayes avatar
Hello together,

I have the impression that my QHY600M has problems with background noise and I am in discussion with my dealer. The camera is second hand and was at the dealer for repair a week ago. After testing it, I notice a background noise even at lower temperatures that I have never seen before. The dealer insists that the noise profile is normal, but I have concerns. The profile shows noise as high as 50k ADU at 0C and 240s. Also at -10C the noise is remarkable hight. Bias images look normal and as expected.
Could someone be kind enough to provide me with some sample images for bias and dark and a uncalibrated light 1x1 and 2x2 for comparison? That would be great.


Thanks

Sven

I've been through the wringer with QHY600M background noise but I can't tell what you have going on from your description.  Can you post a histogram of a light frame taken of a dark region of the sky?  The histogram should show a very tight peak at the low values and you should see stars in the image.  I've had a failed camera produce a "grey" image showing few stars and instead of a nice sharp peak for the background, it showed a large distribution of values in the histogram--up to 50k ADU.  If that's what you are seeing, that camera probably has a problem.  Posting a link to a light and a dark for your camera would be very helpful as well.

John
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Peter Bresler avatar
Peter Bresler avatar
QHY provides good service but it probably means a 2 to 3 month trip to China. One of my 600s is there now because cooling failed.

Peter
Peter Bresler avatar
Peter Bresler avatar
If the camera is under warranty with no signs of use they will provide a refurb from Santa Barbara, Ca.
sjunge avatar
sjunge avatar
Hallo,

thanks for your replies. I have uploaded the bias, darks and 2 lights (crops) to my dropbox. Also a snapshot of the histograms. Compared to a QHY268, the noise seems to be much stronger with the QHY600. 
In the past I have used an ATIK 16200 and the results, especially the uncalibrated images, are much better than with this camera. This really worries me.

Sven

Dropbox-Link:
https://www.dropbox.com/scl/fo/ne3ql09gw2hc1s252fro0/h?rlkey=wnohv9n48bue5facdsn95gve0&dl=0




sjunge avatar
sjunge avatar
John Sikora:
Any particular gain? I've got 1x1 but not 2x2.

Dear John,

I did the first evaluarion w. DSO16 gain 26 offset 30 in 1x1. But also other readout modes and gains could be helpfull as reference. Because of the high night tempearture the lowes temperature I can gain are -15C.

Thanks

Sven
John Hayes avatar
John Hayes avatar
John Sikora:
Any particular gain? I've got 1x1 but not 2x2.

Dear John,

I did the first evaluarion w. DSO16 gain 26 offset 30 in 1x1. But also other readout modes and gains could be helpfull as reference. Because of the high night tempearture the lowes temperature I can gain are -15C.

Thanks

Sven

Sven,
Thanks for doing that!  My first reaction is that what you are seeing is not what I saw when my camera failed.  When I get a little time this afternoon, I’ll upload some good dark files and see if I can find the histograms showing what my camera looked like when it failed.   I’ll also try to take a look at your data to see how it compares.  I’m pretty busy today but I’ll do my best to get back to you ASAP…

John
Well Written Respectful Supportive
sjunge avatar
sjunge avatar
Hi together,

Can any of you provide some darks and bias? That would be very nice and helpful.
Any kind of gain/offset at 10C 1x1 is welcome.

Thanks

Sven