Will a windshield repair kit fix a dinged condenser lens?

Discussion in 'Photography' started by Doc, Dec 13, 2006.

  1. Doc

    Doc Guest

    I accidentally dinged the flat side of a condenser lens with the edge
    of another lens, made a small gouge probably a couple of 1/1000ths "
    deep give or take - I can feel it with a fingernail - and it's quite
    visible when projecting an image through it.

    Will one of these windshield repair kits with a sunlight hardened resin
    make the ding optically invisible - i.e. so that it doesn't cast a
    shadow when projecting through it, or is pointless to try? Don't want
    to spend the $11 if it's not going to work. Is there any kind of repair
    material for this kind of thing?

    If that method isn't going to work, it's my understanding DIY lens
    grinding is possible. Do you think it would be possible to grind down
    the flat side of the lens past the point of the damage? Any links to
    directions on how to do it? Where's a good place to get materials to do
    this?

    I know, the lenses aren't expensive but I hate to waste an otherwise
    good one. I assume it would change its focal length slightly but it's
    probably not crucial for my purposes.

    Thanks for all input.
     
    Doc, Dec 13, 2006
    #1
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  2. Doc

    Colin_D Guest

    It's doubtful that the acrylic resin will have the same optical
    characteristics as the glass; even though it appears the same color the
    refraction and dispersion is bound to be different. That translates to
    image distortion for the rays that pass through the resin.

    Grinding a new flat surface won't change the focal length significantly,
    but it will be a lot of work, hours and hours, and then checking for
    optical flatness is not simple. Far better to junk it and get another.

    Colin D.
     
    Colin_D, Dec 13, 2006
    #2
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  3. It might be less visible than the scratch he has now though.
    Grinding will also remove any coating from that surface. Probably not
    a good idea.
     
    Måns Rullgård, Dec 13, 2006
    #3
  4. Doc

    Ian Stirling Guest

    Colour it in with black marker.
     
    Ian Stirling, Dec 13, 2006
    #4
  5. Doc

    Brian Guest

    Clear varnish is better. Instead, if it is one of a pair of identical
    lenses (convex sides inwards) just reverse the two to get the damaged
    surface away from the focal plane.

    Brian
    Ancient and Modern Optics
     
    Brian, Dec 13, 2006
    #5
  6. Doc

    Brian Guest

    Clear varnish is better. Instead, if it is one of a pair of identical
    lenses (convex sides inwards) just reverse the two to get the damaged
    surface away from the focal plane.

    Brian
    Ancient and Modern Optics
     
    Brian, Dec 13, 2006
    #6
  7. Doc

    darkroommike Guest

    Actually works but something a little more opaque is better,
    you can fill small scratches with India Ink and "dings"
    with black brushing lacquer.
    darkroommike
     
    darkroommike, Dec 14, 2006
    #7
  8. Doc

    Murray Guest

    You might want to try Canada Balsam. It is used to
    glue lens elements together as it has the same
    refractive index as glass.

    Also used to mount microscope specimens on slides
    and a scientific store would be the place to start looking.
    Be warned it ain't cheap. Maybe you know someone
    who works in a lab doing pathology?

    Murray
     
    Murray, Dec 17, 2006
    #8
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