Distortion using a Canon 300d

Discussion in 'Digital Photography' started by ronviers@gmail.com, Feb 10, 2006.

  1. Guest

    I have placed a file here:
    http://photoviki.com/displayimage.php?album=lastup&cat=10196&pos=0

    or if that doesn't work here:
    http://photoviki.com/albums/userpics/10196/ece.jpg

    Even with much help from this group I was unable to do a professional
    job of using arrows to point at the problems. The best I could do was
    to type text directly underneath the problem. I have ordered CS2 so
    when it gets here I will figure out the arrow thing. BTW, these
    problems occur any time I am working with silhouettes. I have only had
    the lens off the camera once and that was to replace the kit lens with
    a prime a few days ago. The distortion I point out in the picture was
    there before I changed the lens, except for the four point star. I
    always keep the camera in a plastic bag because the dust in this part
    of Oklahoma is relentless. The blue dot varies in size, as well as
    some other blue and red dots that I did not point out. The brown dot
    is always more or less in focus.
    Can someone tell me what these distortions are?

    Thanks again,
    Ron
     
    , Feb 10, 2006
    #1
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  2. Pat Guest

    My first guess would be that's it's a flare.

    A flare is light reflecting around inside of the lens caused by a
    bright light shining towards the lens. Set up the silhouette again and
    get it to do it. If it's a flare, it will move around on you as you
    move your camera. That's your first test. Then, take a piece of
    cardboard and place it in between the microscope and the camera,
    directly in line with the light source so no direct light shines on the
    camera. If it's a flare, then it'll go away.

    Then shine a light on a plain wall so it is very diffused and soft.
    Photograph it. It should be okay with indirect light.

    Then, put your lens cap on and take a exposure of 10 seconds or so. It
    should be black (or reasonably close to it).

    If the flare stays in exactly the same place, if the diffused light on
    the wall causes it, if the cardboard doesn't stop it, or if the
    lens-cap test shows it, post the results.

    Good luck.
     
    Pat, Feb 10, 2006
    #2
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  3. Ray Fischer Guest

    <> wrote:
    >I have placed a file here:
    >http://photoviki.com/displayimage.php?album=lastup&cat=10196&pos=0
    >
    >or if that doesn't work here:
    >http://photoviki.com/albums/userpics/10196/ece.jpg
    >
    >Even with much help from this group I was unable to do a professional
    >job of using arrows to point at the problems. The best I could do was
    >to type text directly underneath the problem. I have ordered CS2 so
    >when it gets here I will figure out the arrow thing. BTW, these
    >problems occur any time I am working with silhouettes. I have only had
    >the lens off the camera once and that was to replace the kit lens with
    >a prime a few days ago. The distortion I point out in the picture was
    >there before I changed the lens, except for the four point star. I
    >always keep the camera in a plastic bag because the dust in this part
    >of Oklahoma is relentless. The blue dot varies in size, as well as
    >some other blue and red dots that I did not point out. The brown dot
    >is always more or less in focus.
    >Can someone tell me what these distortions are?


    The star is lens flare. Either remove the UV filter from the lens or
    rent a better lens. The dots are bad pixels in the sensor and are
    quite common in digital cameras. They tend to show up more in long
    exposures.

    The dots are trivially fixed using Photoshop. The flare can be fixed
    in Photoshop as well but it would be a lot harder and eliminating the
    problem in the lens would be best.

    --
    Ray Fischer
     
    Ray Fischer, Feb 10, 2006
    #3
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