What to do with broken EF glass

Discussion in 'Camera Building, Repairs & Modification' started by j-dogg, Dec 19, 2010.

  1. j-dogg

    j-dogg Subscriber

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    I have a 28-90 USM kit lens and an 80-200 f4.5-5.6 both with bad aperture motors (what are the chances) anyway, I know nobody is going to buy these things and they are not worth fixing, they do work when shot wide open though.

    Aside from flipping the lens around what kind of effects can you make with a lens? These things are pretty much F***ed and I figured I would make a use for them instead of just tossing them. I shoot just about any kind of film you could fit into a 35mm camera so I am open to all suggestions, effects, whatever.

    My Canon EF bodies are as follows: Digital Rebel XTi, Elan 7Ne and an EOS 650, neat little camera, was going to flip it but decided to keep it as a backup. No issues with the bodies at all, except the Digital Rebel uses a crop sensor smaller than the 35mm 24 x 36mm format, if that means anything.
     
  2. walter23

    walter23 Member

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    You might be able to find elements in them useful for 4x5 (e.g. on a speed graphic) - any positive element will make an image, sometimes with bizarre effects.
     
  3. ath

    ath Member

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    Take them apart for experiments. Sometimes useful elements are inside; one could e.g. take the mount, some tubing and set up a single element lens for e.g. soft portraits.
    Or use them as loupe, either complete or lens groups from them. I once made a great 2 element loupe for 4,5*6cm slides from a crappy tele zoom lens and some cardboard.
     
  4. j-dogg

    j-dogg Subscriber

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    Hmmm.....I might give that a whirl. What exactly is defined as a positive element, is that usually the first element the light hits? If it's the part I'm thinking of, I've made some neat effects with one of those.

    Any other suggestions I'm open to.
     
  5. hpulley

    hpulley Member

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    Why don't you take them apart and try to fix the apertures? It is possible they are just gummed up. If you can't fix the apertures or can't put them back together again then optical experiments are fun as they say!!!
     
  6. j-dogg

    j-dogg Subscriber

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    Well I took apart the 28-90, I think I know its problem, it's a rather simple fix, just need to clean the contacts that tell the camera what the focal length of the lens is, I see a bunch of feelers down there and I bet it isn't touching the contacts. I might be able to save this one, above 60mm it works fine.

    The 80-200 is definitely project material.
     
  7. Andrew K

    Andrew K Subscriber

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    try cleaning the full aperture switch on the aperture unit - look for the gold pin with the gold spring next to it...

    these get dirty causing the apreture units to play up - clean them with some alcohol and a pair of tweezers - just scrape them clean

    fixes about 85% of them..

    Cheers
     
  8. lxdude

    lxdude Member

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    Positive elements focus light. That is, they cause light rays to converge. It will be convex on both sides, or convex one side and flat the other, or convex one side and concave of lesser curvature on the other. It can be anywhere in the lens.
    If the front element is convex on the front, but more strongly concave on its other side, it will be negative.
     
  9. elekm

    elekm Member

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    These two lenses are "dime a dozen" and commonly available. They're good for experimentation, but I wouldn't put any money toward repairs. They're plentiful on the used market, and it probably will be cheaper to buy two used lenses than to pay to have them repaired.

    The "kit" lenses appear to be made as cheaply as possible.
     
  10. Rick A

    Rick A Subscriber

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    You can always take batting practice with them.
     
  11. moki

    moki Member

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    I'd take them if you were in europe... I never have enough lens elements for building new experimental objectives. Zoom lenses usually have some pretty big elements that can be used for very soft high speed lenses. This way I got a lovely retrofocus (lens to film distance is bigger than the focal length) 28mm/1,65 lens with image circle of about 55mm. That is f-stop one point six five and a lovely fisheye-ish effect for 35mm film.
    My advice: Try to repair it, but if it doesn't work, take it apart and try all possible combinations of the elements until something interesting comes up.