Strange dirt problem

Discussion in 'Digital Photography' started by google.20.jbloggs@xoxy.net, May 22, 2005.

  1. Guest

    I have a D70, about 2 weeks old.

    At very high f-stops, there are 5 or 6 dirt specks on the images, which
    become blurred at lower f-stops. (specks are always in the same place)
    Replacing the lens made no difference, but there is no obvious dirt on
    the sensor, and taking a shot with no lens gives no dirt. Also, if the
    dirt were on the sensor, it would look the same no matter what the
    f-stop, right?

    So it's not the body, and it's not the lens...

    Any ideas???
     
    , May 22, 2005
    #1
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  2. John Bean Guest

    On 22 May 2005 13:50:05 -0700,
    wrote:

    >I have a D70, about 2 weeks old.
    >
    >At very high f-stops, there are 5 or 6 dirt specks on the images, which
    >become blurred at lower f-stops. (specks are always in the same place)
    >Replacing the lens made no difference, but there is no obvious dirt on
    >the sensor, and taking a shot with no lens gives no dirt. Also, if the
    >dirt were on the sensor, it would look the same no matter what the
    >f-stop, right?


    Wrong. The dust particles cast a shadow on the sensor
    (they're resting on the filter above the sensor itself). The
    wider the aperture the softer/larger the shadows. The dust
    will not be visible to the unaided eye, follow the
    recommended cleaning procedure. This may help:

    http://www.cleaningdigitalcameras.com/index.html


    >
    >So it's not the body, and it's not the lens...
    >
    >Any ideas???


    --
    Regards

    John Bean
     
    John Bean, May 22, 2005
    #2
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  3. Cynicor Guest

    wrote:
    > I have a D70, about 2 weeks old.
    >
    > At very high f-stops, there are 5 or 6 dirt specks on the images, which
    > become blurred at lower f-stops. (specks are always in the same place)
    > Replacing the lens made no difference, but there is no obvious dirt on
    > the sensor, and taking a shot with no lens gives no dirt. Also, if the
    > dirt were on the sensor, it would look the same no matter what the
    > f-stop, right?
    >
    > So it's not the body, and it's not the lens...
    >
    > Any ideas???


    It happens. The dirt is actually on the sensor - or just above it, on
    the filter. There are several ways to clean it, some scarier than
    others. I have had good success by holding the camera face-down, doing
    the mirror lock-up through the menu, and then giving it a few puffs with
    a Giotto Rocket air bulb. A little puff or two of gentle air will
    usually get the larger dust strands off the sensor.

    You'll see them a lot more clearly at high f-stops than low f-stops
    because the angle of the incoming light is less. It's the same reason
    you can blur distance at low f-stops.

    To make sure you've got it clean, put a lens on, set it to the smallest
    aperture, point it at a white wall, and take a photo (flash will do).
    Then look at the resulting all-white shot.
     
    Cynicor, May 22, 2005
    #3
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