How to determine if there is dust on ccd

Discussion in 'Digital SLR' started by Nicolae Fieraru, Apr 25, 2005.

  1. Hi All,

    I've been to take some photos with my Nikon D70 camera and I used maximum
    resolution. When I had a look at the photos in actual pixels view, I noticed
    I had around 20 places where the image was showing dark areas. I presumed
    they might come from the lens or filter. I am curious however what is the
    best system to check if there is dust on ccd? I tried an experiment today, I
    took a photo of a blank piece of paper and the image doesn't show any spots.
    I want to know if I need to focus the image on the paper (I think that if
    there is dust on CCD, it should appear as a focused spot on the photo
    despite of an out of focus photo).

    Any advice appreciated. I don't intend to clean myself the sensor, in case
    there is dust on it, I just want to know what is the situation.

    Nicolae Fieraru, Apr 25, 2005
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  2. Nicolae Fieraru

    Jeremy Nixon Guest

    That's right, focus shouldn't matter. Indeed, since you want to be able to
    tell the difference between the dust spots and actual spots on whatever it
    is you're photographing, being out of focus should help matters.

    But, when you do the dust-test shot, it is important to stop down to the
    minimum aperture. Large apertures will hide the dust. So if you saw the
    spots in an outdoor picture shot at, say, f/11, and then did your test
    shot in the house wide open, you've hidden the dust.

    Find a blank white wall that is relatively evenly lit. Shoot a picture
    of it at minimum aperture; assuming it's lit by a table lamp, the exposure
    will be very long, several seconds. During the exposure, move the camera
    around so that any detail in the wall will be completely blurred out of
    existence. Now look for spots.
    Jeremy Nixon, Apr 25, 2005
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  3. Thanks Jeremy, I've done the test and unfortunately now they show up as in
    my photos.... So it wasn't on the lens...
    I just locked up the lens and has a visual inspection, the CCD looks perfect
    to me, can't see any speck of dust on it, therefore I think this is a job
    for a repair shop... It is extremely easy to make it worse and too hard to
    make it better :)

    Nicolae Fieraru, Apr 25, 2005
  4. Nicolae Fieraru

    Stacey Guest

    If you EVER change the lens, you'll just be right back where you are now.
    You need to learn how to clean it yourself or it's going to spend a lot of
    time in the repair shop..
    Stacey, Apr 25, 2005
  5. Nicolae Fieraru

    paul Guest

    Give a shot at just blowing it off. Then try a 'sensor' brush, if the
    dust has been on too long & got glued on with moisture & such, you need
    the volitile solvents and wiping method. It's not too bad though really.
    Theoretically frequest brush treatment could be adequate.
    paul, Apr 25, 2005
  6. Nicolae Fieraru

    Steve Guest

    I have tried something called DSLRClean which are dry stcks you can
    obtain from:

    I was scared of touching the sensor at first but I have managed, with
    some perseverence, to totally clean the sensor on my D70 with these.

    Anyway - do as you will but learning to clean the sensor yourself is
    really the only way unless you leave the same lens on all the time.
    The DSLRClean sticks are relatively cheap.
    Steve, Apr 25, 2005
  7. Nicolae Fieraru

    JPS Guest

    In message <>,
    The sharpness of the dust is related to f-stop. It doesn't matter if
    the subject is in focus or not, other than the fact that it is harder to
    see if the subject in that area is detailed and sharply focused.
    JPS, Apr 28, 2005
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