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Thread: Massive projector lens

  1. #1

    Join Date
    May 2014
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    4

    Massive projector lens

    Hello all,

    First time posting here, but i need some advice.
    I acquired this massive piece of plastic and glass for allmost nothing ( ~10$ ). The seller told me that it`s about 9-10cm diameter ( 3.5-3.9 in ). Perfect for my 5x7 homemade box-in-box paper-negative camera. ( Will post it when it`s done )



    To my surprise this thing has a diameter of 14 cm ( 5.5 in ) and a focal length of about 380-420 mm ( 14-16.5 in ) resulting in a f2.8 aperture.

    The question would be : is this usable with a negative that`s 5x7 ? ( the diameter is grater than the negative width ). I was hoping for a f4..something for portraits..
    I could build a much larger box camera for this, as i can get paper as big as 20x24in but i`ll run into some other problems.

    I also have a few enlarger lenses i plan on using : Eskofot ultragon 150 and 210 mm f/9, zeiss apo-germinar 240,360,450 mm f9. All have f-stops, and thredead mounts. This one has neither.

  2. #2
    Drew Bedo's Avatar
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    Oct 2006
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    Re: Massive projector lens

    You might get a better response to this on the lens forum.
    Drew Bedo
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

  3. #3

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    Aug 2013
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    Chicago
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    Re: Massive projector lens

    I think this would be excellent for portraits. My favorite 5x7 portrait lens is 12", but a couple more wouldn't hurt. I would at least give it a try.

    It would be interesting to figure out how many elements it has, and whether you could saw into the side and add waterhouse stops.
    Thanks, but I'd rather just watch:
    Large format: http://flickr.com/michaeldarnton
    Mostly 35mm: http://flickr.com/mdarnton
    You want digital, color, etc?: http://www.flickr.com/photos/stradofear

  4. #4

    Join Date
    May 2014
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    4

    Re: Massive projector lens

    @DrewBedo : lens forum seems more for "real" large format lens, But i`ll give it a shot, thank you.
    @mdarnton : Seems to have 3 lens/groups ( i can see some edges inside the lens ).

    I`m planning a box for it ( box camera ), format will be a little bigger than 5x7. Paper is 7x9.5in. It has a focus adjustment ( the gearing on the right moves the massive lens inside a plastic barrel ) so the box will not need focusing.
    i`ll dismantle it this weekend. the lens tube is plastic, and has screws, so it can be opened, the case also can be split in two. I`ll post pictures .

  5. #5

    Join Date
    May 2016
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    Licking County, Ohio
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    Re: Massive projector lens

    Do you happen to know where that lens came from?

  6. #6

    Join Date
    May 2014
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    4

    Re: Massive projector lens

    Guy that sold it to me said something about a automatic projector.
    I think it's from some sort of large overhead projector. Judging by the size, something that would be used in a atrium classrom.

  7. #7

    Join Date
    Apr 2017
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    Tucson, AZ
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    100

    Re: Massive projector lens

    I collected quite a lot of projection lenses. Yours is a TV projection lens type. It typically has really short flange distance, with softness and color fringes wide open . Best for experimentation and shooting in black and white. Most focal lengths are typically 140mm f/1 (around 140mm diameter). Since you said this is a 380-420, it sounds hard to believe but it could have happen. I would love to see more pictures before making more accurate assessment.

  8. #8

    Join Date
    May 2014
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    4

    Re: Massive projector lens

    Quote Originally Posted by renditiont View Post
    I collected quite a lot of projection lenses. Yours is a TV projection lens type. It typically has really short flange distance, with softness and color fringes wide open . Best for experimentation and shooting in black and white. Most focal lengths are typically 140mm f/1 (around 140mm diameter). Since you said this is a 380-420, it sounds hard to believe but it could have happen. I would love to see more pictures before making more accurate assessment.
    the focal length is measured empirically : set the lens on a support, looking at something far away ( 250m in my case ). Use a ruler and a matte screen, once the image forms on the matte screen, measure with the tape distance form lens to screen. It gave accurate results for all the other lenses i have ( that have focal length written on them )

    I`ll get some more images. There is nothing written on it .

    Also i plan to use this only with paper negatives, so no problems with colour fringing.
    Last edited by tzava-ro; 21-Feb-2018 at 23:41. Reason: typo

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