Sensor Dust vs "Stuck Pixel"

Discussion in 'Digital Photography' started by telecomm, Apr 1, 2009.

  1. telecomm macrumors 65816

    telecomm

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    #1
    I've got a weird speck showing up in several of my low light photos (high or low ISO, and always in the same spot, so it's not simply high ISO noise). Is this dust? (I thought sensor dust shows up only on light backgrounds.) Attached is a crop of an affected image at 100% magnification.

    Anyway, it's not a big deal as it's easy to remove in software, but it'd be great if I didn't have to! :)

    So, dust, or a problem with the image sensor? (It almost looks like a stuck pixel, and it's always the same color in the affected images.)
     

    Attached Files:

  2. Cliff3 macrumors 65816

    Cliff3

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  3. telecomm thread starter macrumors 65816

    telecomm

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    #3
    Yeah, no luck though. I'm still not sure whether it's dust, or some other sensor issue. It doesn't seem to correspond obviously with any of the specks I see in my sensor dust test shots.
     
  4. Phrasikleia macrumors 601

    Phrasikleia

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    #4
    What kind of camera do you have? I know Canon cameras have a way of resetting the charge to the sensor (or whatever the proper description would be). I had something similar on my XSi, and this quick fix cured it instantly. You do a manual sensor cleaning via the camera's menu option for that, then wait 30 seconds before turning off the camera. Worked like a charm for me.
     
  5. Edge100 macrumors 68000

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    #5
    Sensor dust usually shows up more when stopped down to f/13 or more. Does this increase the size/visibility of the spot, or is it visible at all aperture sizes?

    Just by eye, I'd say it looks like a stuck pixel (i.e. doesn't look like sensor dust I've seen).
     
  6. Phrasikleia macrumors 601

    Phrasikleia

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    #6
    I just realized I should have been specific about what the method I mentioned fixes. It's for stuck/hot pixels, not for dust. And I agree with Edge100, that does not look like dust.
     
  7. telecomm thread starter macrumors 65816

    telecomm

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    #7
    Nikon D60, and there's an automatic sensor cleaning that, by default, runs before turning on and off. There's no waiting 30 seconds, though, so maybe there's something else that could be done...

    Just took some test shots at f/4.5 and f/14, and it's the same size in each. Since it's a bright spot rather than a dark spot, I didn't think it was dust either. But do sensors get "stuck pixels"? I mean, it's not an LCD display. :confused:
     
  8. leighonigar macrumors 6502a

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    #8
    Almost certainly a stuck pixel. You may be able to map it out.
     
  9. Phrasikleia macrumors 601

    Phrasikleia

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    #9
    Yes, my XSi has the automatic cleaning as well (also happens every time I turn the camera on or off), but that won't fix stuck pixels. You have to go into the menus and select manual cleaning, then wait 30 seconds. Apparently there is something different/extra that happens when you do it this way. There's lots on the web about how this method works wonderfully for hot pixels. But maybe it's just a Canon thing.
     
  10. telecomm thread starter macrumors 65816

    telecomm

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    #10
    Selected to clean the sensor from the menu, but as best I can tell it does the same thing that it does on startup and shutdown.

    After a bit of searching around it does seem to be a "hot" pixel. (I hadn't realized that camera sensors were subject to this kind of thing too, since image sensors and LCD screens are probably not all that much alike!)

    Anyway, I'm not too bothered by this, since it's easy to fix and not that noticeable. Of course, I'll probably check that spot in every picture I take now. :eek::D
     
  11. joelypolly macrumors 6502

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    #11
    Looks like a stuck pixel... dust is usually quite big compared to a pixel and easy to clean off.
     

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