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Spots on photos - what's that? (not bad pixels)

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Offline outslider

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Spots on photos - what's that? (not bad pixels)
« on: 18 / December / 2011, 04:37:07 »
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I saw yesterday, that some strange spots appeared on my photos. First I thought, that this is some dirt on the lens, but after cleaning nothing have changed. I tried to investigate this thing.

I can change zoom, but spots seem to be always on the same positions (with only small variations). When I use digital zoom they are bigger and drifted.

I think that this is something, that happened with the image sensor (that would be bad...). Any other ideas? What could be reason of this?

I investigated a few photos from previous days and they look OK, I can't see any spots. I haven't done any long-exposure photos these days and other brutal things to my camera...

Could it be fixed somehow? These spots appear also in DNG. Maybe could I modify dark frame to substract these spots?

Attachments are: 1) photo of the wall with 4s exposure (camera was moved to improve visibility of spots), 2) the same photo with increased contrast (in GIMP).


/EDIT

I was wrong - it's a dirt inside the lens... And still I have no idea how to repair this...
« Last Edit: 18 / December / 2011, 05:23:44 by outslider »
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Offline waterwingz

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Re: Spots on photos - what's that? (not bad pixels)
« Reply #1 on: 18 / December / 2011, 08:45:25 »
Quote from: outslider on 18 / December / 2011, 04:37:07
I was wrong - it's a dirt inside the lens... And still I have no idea how to repair this...
Small screwdrivers,  steady hands, bright lights and lots of patient dissassembly is one option.

Sending it back to Canon is the other.

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Offline outslider

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Re: Spots on photos - what's that? (not bad pixels)
« Reply #2 on: 18 / December / 2011, 09:25:54 »
Well, it's still under varranty, but I'd need to find their service:/ And this way I would have to be more patient, than using screwdriver... I'll maybe try compressed air of or something like this before;)
At the moment, using F=18 and focus set to minimum I can get nice photo of these dirts...
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Offline waterwingz

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Re: Spots on photos - what's that? (not bad pixels)
« Reply #3 on: 18 / December / 2011, 09:37:27 »
Quote from: outslider on 18 / December / 2011, 09:25:54
And this way I would have to be more patient, than using screwdriver... I'll maybe try compressed air of or something like this before;)
Compressed air is only going to move the dirt around - possibly off the back of the lens and into the sensor.

If you think about how a zoom lens works,  and especially how the lens in a P&S camera works,  you realize its really a classical bellows.   Everytime a lens element moves,  air has to move into one cavity and out of another.  As the lense extends, air moves from the outside world into the camera.   Sure,  there are filters in there but you have to change your oil filter in your car periodically and the air filter on your furnace too.    What happens to the filters in your camera as it ages ?

BTW - my success rate with taking apart P&S cameras (to fix lens errors) is 1 out of 2.  The second one ended up in the trash as a bag of small broken parts  :'(
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Offline outslider

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Re: Spots on photos - what's that? (not bad pixels)
« Reply #4 on: 18 / December / 2011, 13:52:02 »
Well, thank you for your answer;) I think that this filters are not good enough, since some dirts appeared a month afer I bought this camera. But they was not seen on photos - some of them had to move in another lens or somewhere, where they got to be visible.

If I use compressed air and it will help it will be good. If not I can always return camera to the Canon:)

1 of 2... too low chance for me!
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Offline reyalp

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Re: Spots on photos - what's that? (not bad pixels)
« Reply #5 on: 18 / December / 2011, 18:04:32 »
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Offline outslider

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Re: Spots on photos - what's that? (not bad pixels)
« Reply #6 on: 19 / December / 2011, 06:33:35 »
Thank you both for suggestions;) With reyalp help I can now use my camera before I return it to Canon and not lost photos!
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