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ian_bird

Starlight Xpress H18 hot column problem

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Hi

I have a Starlight Xpress H18 which has had some horrendous dust problems on the CCD from paint shedding off of the shutter. It was cleaned by SX who also replaced the shutter with a non-painted shutter. But it was still shedding great chunks on the CCD - so it went back to SX again for yet another new shutter with yet another new design and a flush of the CCD circuit board with a solvent.

So now - no dirt on the CCD. But now the CCD has developed a hot pixel column. You can see it here.

post-26501-0-19186400-1353964569_thumb.j

So my question is - is this acceptable? Normal? Can I remove it with Bias frames? Or is this not acceptable?

Hoping someone can advise me. £1,885 is a lot of money to pay for a CCD - I was kind of hoping it would work without problems like this.

Cheers

Ian

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I'm no expert but I wouldn't call it acceptable! :eek: One or two hot pixels may be but not a whole column!

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Hi Harry

Not sure how to measure the ADU. Here is a 1600% zoom on it.

post-26501-0-68769400-1353968807_thumb.j

Wow on the H35 Bias - are you saying that is normal?

Thanks Harry

Ian

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Hi

Yes my Bias is normal

To measure the ADU just place your cursor on a pixel and it should give you a reading also what is the background reading

Harry

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Hi Harry

I am using Maxim DL. Where do I see the ADU?

I must admit - I thought the H18 / H35/H36 were supposed to have really quiet readout noise!

Thanks for your replies - appreciated.

Regards

Ian

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Hi

Its on the bottom line

These line are nothing to do with readout noise , just defects in a chip ( Kodak chips have a lot of these)

Harry

post-4081-0-20346800-1353970704_thumb.jp

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Hi Harry

Thanks for that. So I get 15720 on a hot pixel in the column - and about 14260 on the background (It was a flat). I will shoot a Bias and see what the figures are.

So am I worrying too much about this?

Cheers and thanks for the help.

Ian

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Looking at this again I think it's quite bad. I'll see what the good technical folks think on here but I'm not impressed. The camera was certainly unusable when you came here, that's for sure.

Olly

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Thanks Guys.

This is Terry's reply from SX - makes sense to me. But I will check the Bias tomorrow.

We didn’t build it with a bad CCD and it is still not bad – there is a single hot pixel in the horizontal register which is injecting charge into the column as it reads out. The column isn’t dead and Kodak would just laugh at us for trying to return a CCD with a minor hot column defect. We get CCDs which meet the specification when fitted new and anything cosmetic that happens after that is not covered by any guarantee from the CCD manufacturer, especially as it is probably a cosmic ray hit on the CCD that caused it. This is why I said it is a matter of luck – we can’t control environmental accidents like cosmic rays. I checked your FITS flat and the column is only about 1.5% hotter than the background – it will completely vanish with simple calibration with a bias frame.

Apologies if I maligned Terry and SX.

Regards

Ian

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£1885.00 is top money for what should be a top quality product, i would have thought it would be exchanged for another of the same & to think Martin at FLO exchanged my DMK because i had a few (hot) dead pixels makes me feel like i complained about nothing now.

Hope you get is sorted Ian.

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Hi

If you like you can send me a bias frame and I will have a look :shocked:

But terry usually knows what he is talking about

:evil:

Harry

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