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Thread: 8x10 Meniscus Lens Box Camera

  1. #1

    8x10 Meniscus Lens Box Camera

    This project has been brewing on the back burner for a while; I finally spent several days working at it, was able to get "first light" this afternoon; although there are a few finishing touches still needing to be done.

    I had acquired a lens, salvaged from an industrial machine, a Nikon "stepper" photolithography machine. It's a meniscus, about 4" in diameter, with a focal length of around 10.75 inches. I had envisioned making a nested box camera with removable viewscreen whereby the camera can be operated in two modes: as a "hyperfocal" camera, stopped down to around F90, where critical focusing is not required; and wide open, yielding narrow depth of focus images and requiring focusing on a ground glass.

    This view is from the front. The camera is constructed of 3/16" black foamcore, laminated with a wood melamine-like countertop material. There is a removable aperture plate (made from foamcore) and a masonite shutter in front of it.

    The camera rests on a base; the front of the camera will be afixed to the base permanently (it isn't yet) with the back sliding in and out for focus.


    Attached files

  2. #2

    8x10 Meniscus Lens Box Camera

    Here's a view with the front shutter in the open position. The 3mm aperture plate can be seen (a brass aperture), giving a focal ratio around F/90 at infinity.

    Attached files

  3. #3

    8x10 Meniscus Lens Box Camera

    And here's the lens wide open; the rear aperture plate has been removed. I actually have a ~3" aperture plate made, giving an aperture of F/4 for narrow DOF images, like portraits.
    Attached files

  4. #4

    8x10 Meniscus Lens Box Camera

    View from the rear of the box, looking forward toward the lens. It's mounted in a machined housing that had two mounting holes, which I took advantage of by bolting to mounting brackets. The upper bracket is a piece from an old door lock striker, screwed to a mounting block, that holds the lens in place. I haven't yet painted the inside front of the box; the rest of the interior is covered in adhesive craft felt.

    Attached files

  5. #5

    8x10 Meniscus Lens Box Camera

    A view from the back, minus the film holder. I plan on making a removable view screen, the same size as a sheet film holder, enabling critical focus and composition. Hence the reason why I employed this novel clamping method of holding the film holder in place, without interfering with the view on the screen.

    You can see two black knobs, top and bottom; these push against aluminum "L" channel rails, which clamp the film holder tightly to the camera.

    The "tail board" on the base plate will be long enough to give some good close-focus capability. Attached files

  6. #6

    8x10 Meniscus Lens Box Camera

    A view looking in the film holder slot. The aluminum "L" channel can be seen, its front face covered in adhesive craft felt. The thumb screw pushes the channel against the film holder.

    Attached files

  7. #7

    8x10 Meniscus Lens Box Camera

    Another view of the clamping system for the film holder, this time looking down from above. The thumb screw is clearly visible, able to push against the "L" channel.

    The mating surface between camera and film holder is covered in adhesive craft felt, as are all surfaces that may reflect light from the lens. Attached files

  8. #8

    8x10 Meniscus Lens Box Camera

    First light. It was a stormy day, and I worked hard all day to get the camera to a point where I could actually test it out.

    Not a very thrilling subject matter, my backyard being less than photogenic. Still, it illustrates that the camera does indeed work; no leaks, and the lens is pretty sharp; I didn't have a view screen upon which to focus this image, so it was just guess-work. That, and the F/90 aperture gives pretty good DOF.

    Preflashed grade 2 paper negative, exposure 30 seconds.


  9. #9

    8x10 Meniscus Lens Box Camera

    Second light, 25 second exposure onto preflashed grade 2 paper, F/90.

    The lens appears to be pretty sharp, corner-to-corner, when stopped down; I'm sure it'll get all wild and wonderful when operated wide open.

    ~Joe


  10. #10

    8x10 Meniscus Lens Box Camera

    A very nice camera and excellent first results. A clever system to clamp the film holders with the L-channel.

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