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Old 21-05-2012, 03:14 PM
TrevorW
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QHY 8 OSc and DSS

I've have doubts about my camera which is not quite 2 years old now for a few months.

Recently I had issues about a light band appearing in the top of images, the supplier stuffed DARK foam around the CCD chip to block stray light which seems to have worked.

My gain and offset are set at 3 and 117 yet when stacking images in Deep Sky Stacker (DSS) (around 9 minutes per sub) I end up with a virtually white screen (no detail visible) and no colour showing in the histogram. Apparently this is usual with DSS

After processing in Photoshop the image appears flat and dull, the colour is there after levels etc stretching and saturation adjustment etc.

When I first got the camera I had no issue when stacking images in DSS. Now I have to set the Bayer matrix in DSS at brightness set on 5 for it to register any stars in the image which does not seem normal

A recent image was taken at F9 no reducer. I would have expected more stars to appear in the image because of the length of exposure for each sub and total time stacked image

Anyone with any idea what may be going wrong, thanks
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Old 21-05-2012, 03:26 PM
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bmitchell82 (Brendan)
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Check your DSO post as i have put what i believe may be the issue
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Old 21-05-2012, 03:29 PM
TrevorW
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Ok thanks
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Old 23-05-2012, 10:52 AM
TrevorW
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Another issue when stacking in DSS I have the brightness level set on 5 under the bayer matrix otherwise no stars are detected when stacking

Star count only comes in at around 80-90 even with brighteness level set high which seems abnormally low
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Old 23-05-2012, 04:40 PM
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tlgerdes (Trevor)
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I have the 10 and have never touched the brigthness scale, still at 1:0000
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Old 23-05-2012, 05:42 PM
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[1ponders] (Paul)
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Under your Register settings, what is your star threshold set to? The higher the % the less stars are available. I find around 20% -30% about right. Too low and you have too many stars (10,000+ at times)
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Old 24-05-2012, 10:12 AM
TrevorW
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I have it set low 2% otherwise no stars are detected which makes me wonder about the camera settings etc
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Old 24-05-2012, 10:27 AM
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[1ponders] (Paul)
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2%! That should certainly do it. Was it a gradual problem or did happened from one session to another? What capture program are you using? I'm assuming the images look normal under their native capture program?
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Old 24-05-2012, 10:45 AM
TrevorW
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Using Maxim

The images look fairly normal when captured in Maxim but still not a lot of stars even when a single frame (9 minutes) is stretched in Maxim

I've just resetr the gain and offset in maxim so the average ADU is under 1000 for a .001 second exposure with camera covered. I'm also looking at re-collimating the scope, try and remove all possibilities.

I have the camera options set to high speed download should I un-check this

Regards
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Old 24-05-2012, 11:12 AM
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[1ponders] (Paul)
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1000? What happens if you drop your ADU down to 1? My understanding is that the Analogue to Digital Unit converts the Analogue signal to digital and the that by setting the ADU to 1000 it will take 1000 electrons to convert to 1 ADU. Unless I'm misunderstanding what you are doing. Afaik with the SX camera I use the gain is set at the factory (don't quote me though). The QHY8 has adjustable gain?
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Old 24-05-2012, 11:19 AM
TrevorW
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The QHY 8 has adjustable gain and offset.

http://www.todman.id.au/astronomy/de...n_&_offset.htm

Those settings are as recommended and suggested in the manual, I'm not sure if ADU is the correct terminology refer link

Cheers
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Old 24-05-2012, 11:28 AM
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[1ponders] (Paul)
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Ah yes, Ok, understand now
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