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Thread: Swapping the pinhole with a lens

  1. #1

    Swapping the pinhole with a lens

    Hello everyone,

    I have a simple design in my head but I feel it is a bit silly and way more complicated that it seemed.
    So I have a Goerz Celor 1B, 180mm lens. It is the one with a focusing ability from less than 2 yards to infinity, so I thought that if I would build a box around it similar to a pinhole camera box and would place the film plane 180mm from the iris and focus the lens to infinity then it could result in a sharp image on the film plane. So if I focus with the lens to desired distances it will give sharp images. No ground glass, no bellows just the negative inside the box. The lens should cover 5x7. The core idea was to decrease the extra long exposure times of the pinhole and use a lens instead. Is this idea plain naive?

  2. #2
    Andy Eads
    Join Date
    Jul 2001
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    Pasco, Washington - the dry side of the state
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    233

    Re: Swapping the pinhole with a lens

    Laci, you have a good idea there. Many people have done this before you. So, a little research will reveal numerous designs. Many designs can be used hand held, essentially point and shoot. Using the concept of hyper focal distance, you can build a camera that will deliver an acceptably sharp image over a significant subject distance range. A few considerations come to mind, shuttering the lens, film changing (holders?), and aiming. Have fun! Andy

  3. #3
    Tin Can's Avatar
    Join Date
    Dec 2011
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    13,442

    Re: Swapping the pinhole with a lens

    Not daft but I think you may want to study about how to do it

    I want to do this too

    Plug in your parameters here https://www.dofmaster.com/dofjs.html

    But is also nice to use a bellows and GG to set up what you want to have in focus, then convert to a box fixed focus

    More advice will follow
    sin eater

  4. #4

    Join Date
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    Hemel Hempstead, UK
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    Re: Swapping the pinhole with a lens

    As TC said - you need to be sure of the focus and it's not necessarily the distance from the iris to the film. Focus with a ground glass for your hyperfocal distance, then measure from the ground glass to a convenient place on the lens. The ISO spec for film surface/ground glass matching is 0.007"/0.15mm so it's not as easy as it sounds.

    Neil

  5. #5

    Join Date
    Dec 2001
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    NJ
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    Re: Swapping the pinhole with a lens

    Laci, you floated this idea on photrio.com.

    Short answer, you need a camera back with a ground glass in register with the film plane. You don't have to use the GG when shooting, but you need to focus through the lens when setting up the camera and marking focused distances on the helical.

    Just assuming that because the lens is engraved f=18 cm or something similar its focal length is 18 cm is a bad idea. Focal lengths engraved on lenses are, um, wishes, not reality.

    You could make a dummy camera with a GG or borrow a good depth gauge and a camera with a GG, take the measurements on the dummy or good camera, and then build to match ...

  6. #6

    Re: Swapping the pinhole with a lens

    Quote Originally Posted by Dan Fromm View Post
    Laci, you floated this idea on photrio.com.

    Short answer, you need a camera back with a ground glass in register with the film plane. You don't have to use the GG when shooting, but you need to focus through the lens when setting up the camera and marking focused distances on the helical.

    Just assuming that because the lens is engraved f=18 cm or something similar its focal length is 18 cm is a bad idea. Focal lengths engraved on lenses are, um, wishes, not reality.

    You could make a dummy camera with a GG or borrow a good depth gauge and a camera with a GG, take the measurements on the dummy or good camera, and then build to match ...
    Yes Dan, I know but I felt the need to ask on another forum as well. I see now that Iíve to build a slide box camera with a gg and then build another one. Thanks again!

  7. #7

    Join Date
    Nov 2017
    Posts
    287

    Re: Swapping the pinhole with a lens

    I have something like that. It's a box where I can mount a pinhole that gives me approx. 75mm or I can mount a fixed lenscone with a Fujinon 125mm and use that at hyperfocal f/22. I can use it with standard 4x5 holders. Originally it was only meant to be used with a pinhole but like you I found the exposure times too long unless it is midsummer.

    What I did to get the distance to the film at focus for the lens was to mount it on the Wista. Then measured that hyperfocal distance I had from the calculator Tin Can linked starting at a wall, put the camera there and focussed on the ground glass. Locked everything firm, removed the lensboard and replaced it with a lensboard without a lens. Then measured the distance from front of the lensboard to the ground glass. I should really check if the mounting face of the lens is parallel to the film plane but I haven't yet found a setup (using the means I have) that I trust.

    Here it is with the pinhole:
    https://www.largeformatphotography.i...=1#post1442479

    And so it looks with the lenscone:
    https://www.largeformatphotography.i...d-shoot-in-4x5

    Still some work to do like adding a viewfinder, level and something to use a release cable with the pinhole. And I have a SA90mm lined up as well.
    Expert in non-working solutions.

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