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  1. #1
    Scheimpflug's Avatar
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    Unusual Optical Fixture?

    Does anyone have any thoughts as to the original purpose of this fixture?






    It has one huge lens element and one small lens element, both on a long set of sliding tracks. There is a geared knob which will move the small lens over a very small range, and the small and large lenses are linked together such that they both move together (but at different rates). The whole assembly is very heavy (16 lbs / 7.25 kg) and extremely sturdy. At the end, there is a universal iris diaphragm, a metal plate with a medium-sized circular hole, and then a pair of two moveable bars which open/close on parallel tracks behind it. Everything is lever operated, spring loaded, etc, and built like it would be used frequently.

    Any thoughts on what this fixture might have been used for?

  2. #2

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    Looks like a focusable condenser iris assembly for a microscope light source, probably an arc lamp, judging by the "burn" marks on the iris blades. Kohler type condensers image the filament or arc on the iris.
    Bob

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    It looks a bit like the focusing assembly in an ellipsoidal spotlight. A light source in a reflector goes behind the iris (heavy duty to withstand the intense heat) and is focused with the two lenses. The heavy duty handles would be consistent with a theatrical lighting instrument. Just a guess.

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    That iris looks very close to the Universal Iris's that people use to quickly mount lenses on Large Format cameras. I would see if you can take that part off and if the blade are chunky enough to support a lens. If so use it on your LF camera or sell it- they go for quite a bit of money.

  5. #5
    AgX
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    Quote Originally Posted by Barry S View Post
    It looks a bit like the focusing assembly in an ellipsoidal spotlight. A light source in a reflector goes behind the iris (heavy duty to withstand the intense heat) and is focused with the two lenses. The heavy duty handles would be consistent with a theatrical lighting instrument. Just a guess.
    see here:

    http://en.wikipedia.org/wiki/File:Followspotoptics.JPG

  6. #6
    Scheimpflug's Avatar
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    Quote Originally Posted by Barry S View Post
    It looks a bit like the focusing assembly in an ellipsoidal spotlight. A light source in a reflector goes behind the iris (heavy duty to withstand the intense heat) and is focused with the two lenses. The heavy duty handles would be consistent with a theatrical lighting instrument. Just a guess.
    Bingo! That's it!

    Thanks for the help everyone! I've done a bunch of searching based on these leads, and I'm thinking this assembly may be from a "Strong" brand carbon arc spotlight:


    (image from: http://blog.huntingtontheatre.org/20...spotlight.html)




    It has the same red knobs, in the same locations, and with the same knurled adjustment knob as well.

  7. #7
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    Quote Originally Posted by domaz View Post
    That iris looks very close to the Universal Iris's that people use to quickly mount lenses on Large Format cameras. I would see if you can take that part off and if the blade are chunky enough to support a lens. If so use it on your LF camera or sell it- they go for quite a bit of money.
    That's precisely the reason why I bought it. I just had to buy (and ship ) 15+ lbs of other cool optics along with it.

    The blades are definitely sturdy, so all I need to do is remove the lever and add in the missing knobs which tightened down the iris to hold it in place, and I'm set!



 

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