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  1. #1
    holmburgers's Avatar
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    Unsharp Masking/Contrast Control with Photochromic Glass ("Transitions" lenses)

    Hey all,

    So I'm sure everyone's familiar with transitions lenses, the glasses that automatically turn dark when exposed to light. Well I had a thought about using these for masking in photography, and as is usually the case, I wasn't the first to have this idea!

    Initially I wondered about using it for in-camera (LF) masking to control bright lights, like in a nighttime cityscape for instance, but it's use in printing would certainly be easier and probably more practical to employ.

    I know it has also been used for astrophotography.

    Are there any optometrists around here that might have access to a big sheet of this stuff? I think a single plate of 8x10 photochromic glass could go a long way in a darkroom, and would undeniably be a "game changer".

    Just imagine the possibilities.... and then join me in my search!

    I haven't looked exhaustively, but there doesn't seem to be an easy source for this material.

    Here are some references...
    http://en.wikipedia.org/wiki/Photochromic_lens
    Google "US Patent #4948705"
    http://www.opticsinfobase.org/abstra...=ao-48-19-3570
    Last edited by holmburgers; 07-01-2010 at 11:40 AM. Click to view previous post history.

  2. #2
    ic-racer's Avatar
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    There was a commercial product back in the 70s for masking 35mm slides to do better Cibachromes that was similar. I don't recall the name and searched the internet but could not find reference to it. I may still have an old issue of Modern Photography with an ad for it.

    There was some 'trick' to make the image semi-permanent. Like putting it in water or uv exposure to erase the image and start over.

  3. #3
    holmburgers's Avatar
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    Hmm, interesting. I had thought that it was relatively newer technology, but perhaps not. Maybe I'm just thinking that because of the Transition's lenses.

    One of the patents mentions heat will erase it quicker.

    I saw a optometrists "blank" (for lack of a better term) on eBay once, for cutting to fit frames. So it's around, and it's not prohibitively expensive.

    I'd be very curious to see that Modern Photography ad.

  4. #4
    ic-racer's Avatar
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    Looks like patent #4948705 is similar to the product I remember. The patent is from 1980s, so I may be off a decade. Though, there is probably a delay in getting a patent. I did Ciba around 1975 to 1976 and that is when I saw the ad for the product.

    They DID have the photosensitive glasses back in the 70s. My brother had them.
    Last edited by ic-racer; 07-01-2010 at 11:44 AM. Click to view previous post history.

  5. #5
    holmburgers's Avatar
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    I think Corning makes the glass, maybe I'll shoot them an email for giggles.

  6. #6
    holmburgers's Avatar
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    Check out this Corning ad from the 60's. eBay item #230486163800.... This is exactly what one would need.

  7. #7
    Ian Grant's Avatar
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    Quote Originally Posted by ic-racer View Post
    Looks like patent #4948705 is similar to the product I remember. The patent is from 1980s, so I may be off a decade. Though, there is probably a delay in getting a patent. I did Ciba around 1975 to 1976 and that is when I saw the ad for the product.

    They DID have the photosensitive glasses back in the 70s. My brother had them.
    I remember the product as well, that was when I was doing Cibachromes. It wasn't that easy to control back then, so the idea was quite attractive.

    From what I remember the glass was proposed & tested and written about in magazines, it may have been sold but I can't remember evers seing an advert for it.

    Ian

  8. #8
    ic-racer's Avatar
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    Quote Originally Posted by Ian Grant View Post
    From what I remember the glass was proposed & tested and written about in magazines, it may have been sold but I can't remember evers seing an advert for it.

    Ian
    Yes, a magazine test rather than an advertizement seems right. Or maybe a "new product" blurb.

  9. #9
    Ian Grant's Avatar
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    Quote Originally Posted by ic-racer View Post
    Yes, a magazine test rather than an advertizement seems right. Or maybe a "new product" blurb.
    Also the smallest size was I think 5x4, but maybe they made 4x5 for the US market It may have been smaller but it definitely wasn't 35mm.

    I do remember that I wouldn't be able to use it. I didn't move up to 5x4 until late 76 or early 77.

    Ian

  10. #10
    holmburgers's Avatar
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    I've found some leads. There is a by-all-accounts crappy product for car-shades, however, it probably doesn't work well because a) it has to stick to a window vertically and b) most window glass with block UV anyways, thus rendering its effect useless. It might be fine for our purposes. However, I can't seem to find a "reputable" dealer.... http://www.mybabytravelgear.com/Stay...es-2-Pack.html

    And then there's this website http://www.photochromicwindows.com/ which is also pretty ghetto, but I've emailed to see what the deal is.

    So why would the smallest size of 5x4 be a problem? I was thinking you did the masking at the print, not the negative. But perhaps masking at the negative would work too?

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