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Old Mar 10, 2003, 2:04 AM   #1
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Default artifact in picture question

Hi all

on some of my low light pictures, I am getting an artifact as shown in the example. I am not sure if it was dirty lens or a pixel firing off. Most of my pictures are great but a few have this artifact in different places. suggestions
http://www.pbase.com/image/14133454

kodak dx4900
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Old Mar 10, 2003, 3:55 AM   #2
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If you're talking about that little target-looking blob in the water, it's probably not a problem with the pixels.

It's nice and round, so it may be something on your lens.

Does it move around from picture to picture?
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Old Mar 10, 2003, 7:41 AM   #3
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Did your flash fire? (Check your EXIF data to make sure.) The way the table/bench/... is lit in the right foreground it looks like it might have. With flash pictures a dust particle near the lens can be lit up, and being out of focus, show as a circle.
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Old Mar 10, 2003, 12:40 PM   #4
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Normally when pics take that long to download (56K) I don't bother but this pic looked very promising so I let it go. It's a great picture BTW.

Anyway back to the blob. Strange as it has a pattern - I'm totally confused?????????????? Never seen such a thing.

Anymore pics with this on for us to see.

This blob can easily be removed with cloning.
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Old Mar 10, 2003, 12:42 PM   #5
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Also in my humble opinion I'd clone-out that white thing in the bottom RH corner. I find it distracting.

It's still an excellent foto.
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Old Mar 10, 2003, 6:39 PM   #6
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It could of been a bit of dust on the lens but the pattern it made looked bizzare. I have another example you can look at, you can see a few artifacts. It is easily noticeable if you take a negative of the picture. I will examine the lens of the camera in detail and take some more night pictures to see how they turn up and I will post my results.

thanks
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Old Mar 10, 2003, 6:40 PM   #7
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http://www.pbase.com/image/14160576&exif=Y

almost forgot the site...
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Old Mar 11, 2003, 5:56 AM   #8
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Strange, if you increase brightness in PS a lot, did you realise there are actually about 5 of these things on the pic? One of the spots is transparent with the correct part of the image behind, which suggest either reflection over the light hitting the sensor, or blemishes anywhere from the sensor glass to the lens.

Think I'd try shooting white card in manual, from normal exposure to small stop long shutter from the same position, same zoom - all on a tripod. Then repeat moving the cam slightly right or left, and change the zoom setting - do the spots move?.

On a plain card with a flat field it will be much easier to see what's going on. Also, guess you've tried it, but cap the lens and shoot some long exposure blacks. This will definitely help eliminate hot spot issues and put the lens out of the equation.

I suppose it's not Extra Terrestrial is it!
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Old Mar 11, 2003, 11:33 AM   #9
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Quote:
I suppose it's not Extra Terrestrial is it!
That's it, it's a small alien space ship - why didn't I think of that?
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Old Mar 12, 2003, 10:37 PM   #10
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Well I took a good look and maybe it was just dust, i cleaned the lens and took a few pictures and did not see anything significant. From close examination i noticed a few hot pixels even at 1/32 exposures, I contacted kodak for a suggestion since this is a new camera. Here are a couple examples if intrested, the original pics are big though 4mp
http://www.pbase.com/kschewe/hot_pixels
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