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New CCD Camera, some new problem...


CARAVAN65MAN

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While at the autumn Kelling Heath star festival in September, we all had some good clear nights, some better than others, 4 out of 5 for me in fact.  It did give me ample opportunity to try out my new OpticStar DS145C ICE CCD Camera for real, getting image exposure lengths from 60 to 600 seconds auto-guiding.  For five years I've been using a Canon DSLR (1000D) and so using a CCD was a completely new ball game, and I mostly enjoyed just about everything about it.

Then came my first gremlin, I noticed a lighter patch in my images in the top left hand corner, and have since learned this is called AMP GLOW.  There is very little written about it, and the retailer said it is common-place with CCD cameras and advised me to use accompanying Dark Frames to subtract  and they will remove the glow.

I would appreciate to know if anyone else has experience with such a problem and would compare notes with me, and perhaps I can move forward again, without feeling I have perhaps picked a bit of a' lemon' for a camera.

Thanks

CARAVAN65MAN

Please see an example with this post.

M27_10mins_gain3_iii_01_bin_sum2x2_lvs.tif

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I can't say that amp glow is a common feature of ccd cameras, in fact it's quite uncommon and only affects a very small number of of ccds. If anything, its more a feature of cmos technology.

However, all is not lost! Take some matching dark frames and that should sort it out.

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Hi,

I just looked at the Diffraction Limited link that Ken posted. I quote

Readout Amplifier Glow

'All semiconductor devices emit light when power is applied. The readout amplifier in the corner of a CCD array therefore creates a small amount of light when it is powered up. This causes a bright spot in the corner of the array. This is often minimized by partially powering down the amplifier during integration, and then restoring it to full power during readout.'

I am not a semiconductor expert but I am reasonably confident that this explanation is just plain wrong! They don't!!!!!

Can someone who knows more about this comment please?

Regards, Hugh

New Edit - A bit more research suggests the cause is heat / IR radiation. Technically it is light so I am wrong!!

Regards, Hugh

 

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When I had a QSI690, there was a problem with some of the camera's that they had amp glow on long exposures...... It WAS indeed sorted out with darks. But QSI did take all of the affected camera's back free of charge and did, I believe, a firmware fix that sorted the amp glow out.... it went after that :)

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If I use darks I don't get it at all. I prefer not using darks (I prefer bad pixel mapping) but this does leave me with a small amp glow just in the bottom right hand corner. I can fix this in 60 seconds or less using Ps Burn tool set to shadows. I would rather do this than use darks which, on my setups, seem to be more invasive.

Olly

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