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Thread: LIght Pipe Array Camera

  1. #1

    LIght Pipe Array Camera


    What is it?

    Here's another clue:


    It's nowhere near finished into a working camera, but the array part is done. It's a newfangled contraption that I done dreamed up, the basic idea being a diverging pyramid of thin light pipes, each of which captures a narrow angle of view and directs it to a specific spot on the film plane. Unlike a glass lens, pinhole or other refractive optic, the Light Pipe Array doesn't invert the image at the film plane.

    The background story on this is that I had purchased several packages of these thin, black plastic stir sticks (which I could only find at Target stores), to be used in a now dormant upgrade to my Pixellator camera project. But looking through a cluster of these sticks one day, and seeing a somewhat coherent image, my mad scientist's brain began to churn.

    Here's a blog article with more details.
    http://joevancleave.blogspot.com/201...rializing.html

    Now that I've posted this, I have further incentive to finish it and get some paper negatives (or Harman DPP) exposed. And I have no idea what the shutter speed will need to be; it might require a sub- 1 second mechanical shutter, which should be fun, considering the size of the array (the front baffle being over 8" square).

    ~Joe
    "There was just that moment and now there's this moment and in between there is nothing. Photography, in a way, is the negation of chronology."-Geoff Dyer, "The Ongoing Moment"
    My Writing Blog: Joe Van Cleave's Blog
    My Pinhole Blog: Obscure Camera
    Visit my F295 Gallery

  2. #2
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  3. #3
    Can you calculate exposure based on a pinhole of similar size and distance from the film? The mystery will be if it produces a coherent image or if it produces a pattern of overlapping images like a multifaceted bug eye, might depend on the length of the tubes.

    What about reflections down the length of the tubes? Have you tried exposing a single straw on a small piece of paper to see what it looks like or are you going all in no matter what?

  4. #4
    Thanks for all your comments.

    Greg, that's a great idea. I'll have to do some calculations with the straw's length divided into its diameter as a starting point for an assumed focal ratio, then see what kinds of shutter speeds my light meter recommends.

    As for reflections down the tube, I've seen them indirectly by projecting light from the array at a white paper screen; each pixel can give a unique signature, as the reflections are all different. That will have to be taken into account when figuring exposure times.

    A quick rundown of the numbers suggests either a mechanical shutter or some filte/diffusion screen might be needed. Say the straws are 5" in length, with 7.5 straws to the inch. That's around F/37, not counting additional exposure from reflections. I might be able to use a lens-cap style of shutter with slow paper like Harman DPP under shaded daylight conditions. More testing is obviously required.

    And I suppose I'm sufficiently emotionally invested in this project to say I'm "all in"!

    ~Joe
    "There was just that moment and now there's this moment and in between there is nothing. Photography, in a way, is the negation of chronology."-Geoff Dyer, "The Ongoing Moment"
    My Writing Blog: Joe Van Cleave's Blog
    My Pinhole Blog: Obscure Camera
    Visit my F295 Gallery

  5. #5
    How about a darkslide shutter, that way the area will be much smaller.

  6. #6
    Greg, that's what I was thinking. Or if a bit more speed is required, a spring-operated shutter directly in front of the film holder. "Cheating" would be using a sheet of dark film as a makeshift ND filter, to cut down the light enough to use a hand-operated shutter reliably.

    On my blog, someone commented about using fiber optics instead of tubes. I thought about this, then it struck me that, aside from the cost, and the problem of cutting the ends of the fibers to an optically-precise plane (there are cutters for that application, but they can be expensive, especially considering how many cuts would have to be made), and the precise assembly required of (literally) thousands of glass fibers in close proximity, there's the problem that the ends of the glass fibers "see" a wide angle of view, and so each fiber doesn't act like a light pipe, which only sees a narrow field of view.

    Thanks again for all the comments, keep the good suggestions flowing.

    ~Joe
    "There was just that moment and now there's this moment and in between there is nothing. Photography, in a way, is the negation of chronology."-Geoff Dyer, "The Ongoing Moment"
    My Writing Blog: Joe Van Cleave's Blog
    My Pinhole Blog: Obscure Camera
    Visit my F295 Gallery

  7. #7
    That's the same thing I thought about the fibers.

    There are many small metal tubes that you might be able to use to get smaller diameters, but not going to be as cheap as straws. You might find smaller diameter plastic capillary tubes, but not sure you will find them that are light proof or rigid.

    For the darkslide shutter, I was thinking you could cut a slit and pull this across the exposure area. That should get exposures down to 1/10 second or so.

  8. #8
    Yep. The travelling slit shutter is a good idea. I could use various sized slits for a variety of shutter speeds, as required.

    K & S Engineering sells various sized metal tubing through their retail displays. Their catalog shows the smallest brass tubing available to be 1/32" OD, .020" inside diameter, .006" wall thickness. Yea, rather pricey for a higher resolution camera in 8x10 format size, I'm assuming, unless I arranged for a bulk purchase. I like the idea of brass because it can be easily soldered together if need be.

    ~Joe
    "There was just that moment and now there's this moment and in between there is nothing. Photography, in a way, is the negation of chronology."-Geoff Dyer, "The Ongoing Moment"
    My Writing Blog: Joe Van Cleave's Blog
    My Pinhole Blog: Obscure Camera
    Visit my F295 Gallery

  9. #9
    Check Mcmaster-carr, I bet that same brass is cheaper. But it is still brass and that makes it expensive.

  10. #10
    Used to be able to buy long lengths of needle grade bulk stainless tubes, might want to check on that and just super glue or epoxy them together. Somewhere I still have some of this around, really small stuff. I miss the days when Smallparts.com used to carry really good stuff.

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