canon 20d spots in blue sky

Discussion in 'Digital Photography' started by Robert, Feb 21, 2005.

  1. Robert

    Robert Guest

    I have my Canon 20D and think its a great camera except for one difficulty.
    Wondering if anybody else has noticed that in outdoor shots with a lot of
    blue sky finding spots.
    I bought my camera from circuit city and the first one had over two dozen
    spots in the blue field.
    I returned the camera and had it replaced, this one has two spots that I
    have found and they are not small spots.
    It appears the problem only is noticeable with a lot of sky blue and not
    noticeable in a standard shot. These are not
    "SMALL" spots but very noticeable to me. The spots are an entirely different
    pattern on the new camera..

    Guess I will have to take primary color shots and check it out.
    Robert, Feb 21, 2005
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  2. Robert

    Mark² Guest

    If you're talking about irregular spots...that are NOT defined clearly by pixel, then you
    are most likely dealing with dust on your sensor. This can be fairly easily fixed by
    following the directions for sensor cleaning in your manual.

    Dust on the sensor creates slightly darker portions in your image, which show up as blobby
    areas. There is nothing wrong with your camera if this is the case. The sensor just
    needs to be cleared.
    Mark², Feb 22, 2005
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  3. Robert

    Robert Guest

    Does this show up as only being in the blue areas ?
    Be glad to send a photo to you with spots if you could tell me its dust,
    seemed unusual I would have dust on two new cameras and I did a mirror
    lock and inspected the sensor but could see nothing.
    Robert, Feb 22, 2005
  4. Robert

    Mark² Guest

    It is often only noticed in sky portions.
    If you send me an image, I'll be able to tell you if it's dust.
    Try taking an imabe of a light green piece of paper, or light blue, or any other light-ish
    color that doesn't have much texture.

    anyway... Send me a photo if you like.
    I can accept up to 4MB files.
    Just make changes to my e-mail address as indicated (when you try to reply).
    Mark², Feb 22, 2005
  5. Our eyes are particulary sensitive to blue, and spots are easier
    If you take pictures of any bright uniform background using aperture 22 or
    smaller any dust will show up. Treating the picture in Photoshop with Auto
    Levels makes the spots darker and easier recognizable.

    The dust particles are too small to see by the unaided eye, and are attached
    to the sensor by electrostatic charges.

    As I recall there is no good instructions in the manual for removing dust,
    only large particles/hair using a large blower. Do NOT use compressed air!
    If you want to remove it yourself you can get better advise at or

    All manufacturers charge the customer for cleaning of the sensor. Some
    cameras are already dirty when you buy them, but eventually all will get
    dirty after some lenschanges.
    Frode P. Bergsager, Feb 22, 2005
  6. Robert

    Jim Townsend Guest

    It's probably dust.. Put your camera in Av mode and select a small
    aperture.. Around f/22. Now take a shot with a lot of sky. If the
    spots get worse, (more pronounced and more of them) then it is dust.

    Also.. Dust spots will always be in the same place..
    Jim Townsend, Feb 22, 2005
  7. Robert

    C J Campbell Guest

    Well, not always. Dust can be stirred up and move. That is how it got there
    in the first place. But generally it won't move much between consecutive
    C J Campbell, Feb 22, 2005
  8. Robert

    C J Campbell Guest

    Almost certainly dust spots. Camera manufacturers tell you not to clean the
    sensor yourself, but there are two fairly safe methods that work extremely

    The first is called the Copper Hill method. You can find it here:
    This site also has sample photos of what dust looks like, so you can decide
    for yourself. The manufacturers use a slightly less sophisticated version of
    the Copper Hill method.

    More expensive, but arguably more effective, is the special sensor brush
    made by Visible Dust. This is probably safer and better than the cleaning
    method the manufacturers themselves use.
    C J Campbell, Feb 22, 2005
  9. Robert

    Jim Townsend Guest

    True.. But the most annoying specks are usually the most tenacious :)
    Jim Townsend, Feb 22, 2005
  10. Robert

    Sheldon Guest

    I think everybody here has covered your problem, but now you know where all
    those UFO photos come from. :) I used a large blower bulb to get rid of my
    dust problems. Worked like a charm. The only reason the "spots" seem to
    appear in the sky is because it's just one big blue pallet they easily show
    up against. Actually, one of the best tests for dust is to take a shot of a
    clear blue sky -- filling the entire frame with sky. If there's any dust it
    will show up. Welcome to the world of DSLR's.
    Sheldon, Feb 22, 2005
  11. Robert

    Robert Guest

    Thanks everyone for all the assistance. I looked at the sample photo at the
    copperhill site and
    it convinced me the problem is dust. I do appreciate the help and
    information and must say its a great camera.
    Robert, Feb 22, 2005
  12. Robert

    Stacey Guest

    Glad I don't have to deal with this... :)
    Stacey, Feb 22, 2005
  13. Robert

    Harvey Guest

    Will high-end point and shoot cameras like sold by Canon, Nikon, Olympus and
    Panasonic also get dusty? Will the dust eventually penetrate the seals or
    is that not likely to happen?
    Harvey, Feb 22, 2005
  14. Robert

    Chris Brown Guest

    Chris Brown, Feb 22, 2005
  15. Robert

    Skip M Guest

    There will come a day when even the ultrasonic vibrating sensor of the Oly
    will encounter a bit of dust so tenacious as to remain despite its, and
    your, best efforts. Especially if you get cocky about how "dust free" the
    Oly will stay.
    I have an "L" shaped bit of dust that has so far resisted all attempts to
    remove it, bulb, swipes, whatever.
    Skip M, Feb 22, 2005
  16. Robert

    C J Campbell Guest

    Humans are filthy, what else is there to say? We all just walk around in
    huge clouds of dust, like Pigpen.
    C J Campbell, Feb 22, 2005
  17. Robert

    Owamanga Guest

    When the Olympus shakes the dust free... where does it go?
    Owamanga, Feb 22, 2005
  18. Robert

    Ton Maas Guest

    Check out the special animation at the Oly website. It explains the
    process very well.

    Ton Maas, Feb 22, 2005
  19. Robert

    Hils Guest

    C J Campbell wrote
    It's not just humans, it's the universe: everywhere we look into space
    it's there! Next time you see a spectacularly colored sunset or lunar
    eclipse, they're only like that because someone or something has chucked
    a load of dust into the air. :)
    Hils, Feb 22, 2005
  20. Robert

    Larry Guest

    From what I read, it is SUPPOSED to fall onto a little "Sticky" patch put
    there to catch it (I wonder what happens when its "full"???)
    Larry, Feb 22, 2005
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