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  1. #1
    holmburgers's Avatar
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    Fresnel Lens As Imaging Lens

    I bought a cheap page magnifier for the purpose of putting it on my GG.

    In the meantime however, I've been playing with it; holding it up to a wall opposite a bright light and observing its imaging abilities.

    The image it creates is wonky to say the least, but it's also quite interesting. It is also very bright!

    I'm wondering a couple things. First, what would the f/ stop be? Finding the focal length would be simple enough, but how much of the diamater should I consider as lending to the maximum aperture, if that makes sense.

    The other thing is whether or not creating a simple aperture/mask will increase the quality of the image. I'll experiment with this when I get home and see what the result is.

    At any rate, if you've got a fresnel lens, take it out and play with it. It might have some potential for interesting images.

    Anyone ever done this?
    If you are the big tree, we are the small axe

  2. #2
    Whiteymorange's Avatar
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    Never done it but, as an inveterate explorer into things that no one in his left mind would ever do, I say GO FOR IT! Try an educated guess on exposing a paper neg and adjust as you go. Paper isn't that costly and the process is simplified if you have a darkroom set up for printing.

  3. #3
    ic-racer's Avatar
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    Its just like a regular plano-convex lens, they just take out the middle bulky part . So the aperture is the diameter of the lens sheet.

  4. #4
    holmburgers's Avatar
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    Thanks guys. That makes it probably less than or very close to f/1.

    I have no idea about how to go about making a camera of this sort however. The shutter specifically. Some kind of crude, perhaps cardboard, focal-plane shutter might be the best bet.
    If you are the big tree, we are the small axe

  5. #5
    Andrew O'Neill's Avatar
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    I did this a few years ago with a box camera that I made. Make yourself an apeture out of black construction paper. I made myself a set of three. Image quality improves with smaller apetures. Got some interesting images.

  6. #6
    holmburgers's Avatar
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    Hey Andrew, that's great. Got any examples easily accessible?

    I just made some paper apertures to fool around with. I wish I had a Graflex with the focal-plane shutter and I'd just make a lens-board out of a fresnel.
    If you are the big tree, we are the small axe

  7. #7
    tomalophicon's Avatar
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    You shouldn't need a shutter with paper negatives. That sounds like fun, let us know how you go.



 

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