Disconcerting Image Features

[niteman1946]

Hi Group,

I don't post here much, mainly because my 383L+mono has worked well.  But, I've just noticed a couple of persistent image features that can be seen on my flats.
The attached image shows three shots of the left hand side of the same flat.  All three are highly stretched to illustrate the problem.
From left to right:
1.  Left hand edge of full flat image, highly stretched.
2.  Left hand lower corner of item 1.  This is highly magnified and just a hint (smudge) of it can be seen in the full flat image.  Note the somewhat honeycomb pattern.
3.  Left hand upper edge of image 1.  Highly magnified, this semi-circle (or bubble) can just barely been seen adjacent to the "R" of "GRN" in image 1.

These are neither moisture nor ice.  They persist whether the cooler is set above or below freezing.
My concern is they show indications of image chip deterioration.  So far, they are small and have little affect on a finished image.  But are they signs that the chip will continue to deteriorate?

Appreciate your help.
Thanks,
Mark
 

[chrisjbaileyuk]

Mark

Worrying! I have a couple of darker patches on my 383 that are neither debri on filters or the CCD window. These have grown, slowly but surely, over the past year.

Do your artefacts show on dark frames (which would indicate more of an electronic issue) or only nn flats/lights (more suggestive of an accumulation of something on the cover slip)?

Chris

[niteman1946]

Hi Chris,

Thanks for your response.  I looked at my current darks and do not see these features.  However, these darks are a bit old, so I'll shoot some tonight and re-inspect - and repost with the results.

I'm assuming your term "cover slip" is the glass in front of the image chip.  That's an interesting thought that it could be crud there.  We will see.

Sorry to hear of your problem.  While I suspect Atik would do a proper repair, the cost of money and especially time would be frustrating.  Good luck there.

Mark

[chrisjbaileyuk]

Mark

Have a look at the CCD with a magnifying glass and see if you can see anything. I can just about make out the two areas on mine that show up faintly on light frames. If I get any sort of frosting, it always starts in these two zones. Flats sorts mine pretty well so I am not too worried for now and the old gal has now taken an awful lot of frames.

Chris

[chrisjbaileyuk]

ps

looking at your images again, are you sure its not frosting? When did you last refresh your dessicant tablets? I have found it to be a two stage affair. Take them out and bake them. Replace and leave for 24 hours. Take them out and rebake before finally replacing.

[niteman1946]

Hi Chris,
Thanks for the follow-up thoughts.
First, I've not tried new darks yet (other demands on my time).  But I will post when I do.

We're moderately humid around here and often I have to just work around the frosting.  It does dissipate after several test shots.  But I've not seen a correlation twixt the frosting and these features.

I agree with your drying routine.  I had done the double desiccant technique just prior posting the images.  And there was no frosting during these sessions.  That's why I stated with confidence that the features were not a water/ice thing.

Mark

[niteman1946]

Chris,
As a follow-up, I shot a fresh Dark last night.  If the two features are there, they are impossible to see with a stretched and enlarged image.
For now, I'm taking the position that they represent grunge on the cover glass and will try to remove them at the next tear-down.
Thanks for your help,
Mark