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  1. #1
    jpreston's Avatar
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    Orbit lens question

    Anyone know what is the longest lens I can use on an Orbit 4x5? I think John said it has a 22" rail.

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    jpreston's Avatar
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    Thanks!

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    Depends on how close you want to focus.

    For normal (non-telephoto) LF lenses the focal length, say 250mm (roughly 10"), is also roughly the distance from the film plane to the lens board when focused at infinity. If you want to focus on something closer than infinity then the distance between film and lens board has to get longer.

    To focus on something 20" (500mm) from the lens board with a 250mm lens the distance from lens board to film needs to be 20" (500mm) so your 22" (550mm) rail should work very nicely with a 250mm lens. A 300mm lens will probably work for most situations but the close focus point is going to be out a bit farther, a 500mm lens will just focus on considerably more distant subjects and be useless for close subjects, a 600mm lens would probably never find focus on your camera.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  5. #5
    jpreston's Avatar
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    Quote Originally Posted by markbarendt View Post
    Depends on how close you want to focus.

    For normal (non-telephoto) LF lenses the focal length, say 250mm (roughly 10"), is also roughly the distance from the film plane to the lens board when focused at infinity. If you want to focus on something closer than infinity then the distance between film and lens board has to get longer.

    To focus on something 20" (500mm) from the lens board with a 250mm lens the distance from lens board to film needs to be 20" (500mm) so your 22" (550mm) rail should work very nicely with a 250mm lens. A 300mm lens will probably work for most situations but the close focus point is going to be out a bit farther, a 500mm lens will just focus on considerably more distant subjects and be useless for close subjects, a 600mm lens would probably never find focus on your camera.
    So much to learn about this large format stuff! Thanks for the info.

    Jeff

  6. #6
    shutterfinger's Avatar
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    Specs in the link above says bellows draw is 16 inch.
    Large format press cameras with rangefinders have a maximum of 1 1/8 inches/28mm of movement from infinity to end of travel/closest focus distance.
    Applying that to the specs a lens that will infinity focus at 14 7/8 inches from the film plane is usable. 1 1/8=1.125; 16-1.125=14.875; 1 inch = 25.4mm; 14.875*25.4= 377.825mm.
    A 350-360mm lens will focus to 10 to 15 feet on a 16 inch bellows for standard photography.
    For 1:1 a 8 inch/203mm lens is the longest that can be used.
    Telephoto lens are another subject for someone else to discuss.

  7. #7
    markbarendt's Avatar
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    Quote Originally Posted by jpreston View Post
    So much to learn about this large format stuff! Thanks for the info.

    Jeff
    Yep, lots to learn.

    Lots of info here:

    http://www.largeformatphotography.info/
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  8. #8
    jpreston's Avatar
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    Quote Originally Posted by markbarendt View Post
    Yep, lots to learn.

    Lots of info here:

    http://www.largeformatphotography.info/
    I've been doing some reading there. Lots to learn...

  9. #9
    jpreston's Avatar
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    Quote Originally Posted by shutterfinger View Post
    Specs in the link above says bellows draw is 16 inch.
    Large format press cameras with rangefinders have a maximum of 1 1/8 inches/28mm of movement from infinity to end of travel/closest focus distance.
    Applying that to the specs a lens that will infinity focus at 14 7/8 inches from the film plane is usable. 1 1/8=1.125; 16-1.125=14.875; 1 inch = 25.4mm; 14.875*25.4= 377.825mm.
    A 350-360mm lens will focus to 10 to 15 feet on a 16 inch bellows for standard photography.
    For 1:1 a 8 inch/203mm lens is the longest that can be used.
    Telephoto lens are another subject for someone else to discuss.
    Great! So a 360mm lens would work for a longish lens, then. I've read that true telephoto lenses don't need as much draw as non-tele types.

    Thanks,

    Jeff

  10. #10
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    I believe my 5x7 Orbit has the long rail, maybe 22", but I can't check on it at the moment. Some of its details differ from the 1968 catalog. It makes a great studio camera with a 4x5 back.

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