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Zig-Zag noise pattern on CCD image


KevinReid

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I had a try with a QSI683 at -20C on Panstarrs last night (yep amazingly, it was clear for a while around 10pm to midnight). The attached 60s luminance filter shot has a regular zig-zag pattern that I got consistently - unfortunately I can't upload the FITS file as I am limited to 1Mb so I have attached screen shot that shows the kind of thing I am talking about. I am using a good quality 3m USB lead and wonder if anyone has seen this kind of thing before? If it were an artefact of the setup I would have expected to get the same pattern on my darks but they just show a randon noise pattern. Any help greatly appreciated. Thanks!

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This might sound daft, but could light cloud cause this kind of effect as it moves across the sky during the image? I just can't explain the regular nature of the pattern. I can't upload the FITS file which is 4Mb - perhaps because I am new to SGL I am limited to 1Mb uploads?post-17373-0-68698400-1400954958.gif

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Hi Kevin,

No problem.  

Is if the first time you have used the Camera? Have you tired it again since last night, It could be there was some electrical interference near the camera. Try as the link suggest and take a bias frame. I do get a little sometimes in my Bias frames and put that down to the cooler, so try the bias with the cooler on and also off see if there is a difference.

Let me know the results.

Regards

Steve

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I definitely would look at checking the power supply and also interference from a data cable near to the power perhaps. Your retailer will probably like to know that you have tried to eliminate certain things. Take a bias too and see how that fares.

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Thanks for all of the useful replies. I'll have a play tomorrow and give some feedback. I am using a UPS so the mains will be filtered. I'll look for anything near the data lead that could introduce the interference, and I'll also try the cooler off. I have a regulated 13.8V psu which I could use to power the QSI683 directly rather than use the supplied mains psu through the UPS. Anyway, I have lots of things to try out :) 

Its not the first time I have used the camera and the pattern is not always there, so I am hopeful that it is something simple like the placement of the data lead in relation to a power cable.

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Definitely electronic interference of some kind - a process of elimination by disconnecting everything but the camera and capture PC (and trying a different PC as well) should track this down, especially as it is so severe. I'd be tempted to take the UPS out of the equation early on as, if this has a fault, you could easily introduce a 'ripple' on the supply rail.

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Strangely I cannot replicate the problem, I've tried laying the data cable next to the QSI psu and running all of the other equipment I normally have going (Lodestar, telescope fan, mount, cooler). I've tried looking at bias frames and 60s frames and played with the stretch - just random noise. So I hope the camera is OK. I guess I'll just have to wait for it to occur again and then start eliminating components. Looks like a clear night tonight so I'll get back to Panstarrs and try it again :). I'll let you good people know if I find the source.

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