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  1. #11
    Jerevan's Avatar
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    Premo, you can get the same effect as shown above with a simple close-up lens. There's a formula for deciding the actual focal length (which I don't remember right now) but try a +2 close-up lens for a start and see where it gets you.
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  2. #12
    Joe VanCleave's Avatar
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    Quote Originally Posted by premo View Post
    I/m very impressed with the quality of the meniscus lens---especially the still life of the bananas. Is there a place to find these lenses for sale? I would like one to use on my R.O.C 8X10 with about an 18" focus.
    I sure any single-element meniscus will give similar results; you can find these at optical places like Edmund Scientific and such.

    This particular lens was salvaged from a Body 9 Nikon Stepper, used in the semiconductor industry to print circuit patterns on silicon wafers.

    I've also since acquired a Fujinon Xerox 240mm lens assembly; it projects a pretty good image wide-open, but can't be stopped down using my usual method of waterhouse-type aperture stops on the front or rear of the assembly without severely vignetting the corners of the image. The ideal location for these aperture stops would be inside the lens assembly itself, between the lens elements. So for now, this new lens is used under dim indoor light for still-lifes and portraits.

    Here's a view looking inside the camera, with the Fujinon Xerox lens installed:


    Here's a still life from the new Fujinon Xerox lens:


    Here's a shot of the viewscreen (digital camera upside down) focused on my workbench:


    Here's the new removable mechanical shutter that fits onto the front of the box camera. Still a work in progress. Rube Goldberg is rolling over in his grave...!!:


    ~Joe

  3. #13
    Barry S's Avatar
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    That shutter is amazing, Joe. How about a video of it in action?

  4. #14
    2F/2F's Avatar
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    Quote Originally Posted by premo View Post
    I/m very impressed with the quality of the meniscus lens---especially the still life of the bananas. Is there a place to find these lenses for sale? I would like one to use on my R.O.C 8X10 with about an 18" focus.
    Keep in mind that you are seeing a digitized reduction of the negs.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  5. #15

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    I love the still lifes. And that shutter could do some real damage. Where do you insert the victim's thumbs when seeking to extract information?

  6. #16
    Joe VanCleave's Avatar
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    Here's a full accounting of the shutter, over on F295. I don't yet have any video of it in action, but rest assured, one should take caution when it fires lest any unnecessary digits get lopped off in the process!

    One more image taken with the Fujinon Xerox lens wide open indoors:

  7. #17

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    I made something similar a few years back to see if I wanted to get into 11x14. It closed into a box that when opened the front and back covers became the bed for the extension, about 34". It used homemade film holders and the ground glass was removed when inserting the film holder which was secured with a couple of sliding tabs. Since focusing was a bit "sticky" I eventually put axles with HO gauge train wheels on the two boxes and grooved the bed to hold HO gauge rails and built in a couple of screw locks. After I decided I wanted to pursue the format I built a camera out of aluminum with bellows, full movements etc that was a rail design but could be broken down for transport in the field.
    "Fundamentally I think we need to rediscover a non-ironic world"
    Robert Adams

  8. #18
    Mark Fisher's Avatar
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    For pretty much any size meniscus lens you want, look at Anchor Optics (cheap, commercial grade) or Edmund Optics (expensive, very complete selection). Surplus Shed is another great, cheap source. BTW, plano-convex and double convex lenses make equally great single element lenses. They get more fun used with a larger aperture, though (:

  9. #19

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    At Surplus Shed, they have a lens finder. The dropdown lists both negative and positive meniscus lenses. Which one should you buy for a single lens camera? I don't have a clue, but I have always wanted to try one out.

    Jon

  10. #20
    Joe VanCleave's Avatar
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    You want a plano-convex, bi-convex or convex-concave lens, either of which is a positive type of lens. A negative lens is like a bi-concave lens, one that won't focus a projected image.

    Then you want to select your focal length. This is mainly a personal preference based on expected angle of view with your desired film format. Figure a focal length that's near the diagonal of the film format is a "normal" angle of view. There may also be physical limitations of your camera setup, especially (like in my case) one's that are handmade and are limited by minimum or maximum focal length.

    The diameter of the lens has to do with your maximum aperture (focal length divided by lens diameter). Keep in mind that with single-element meniscus lenses, wide open apertures have only a very narrow sweet spot, in the middle of the image, that is sharply focused. So therefore expect anything under, say, F8, to be pretty soft with totally out of focus edges. Therefore you can save some money on these lenses by opting for a smaller diameter lens; the extra diameter doesn't buy you much more usably sharp image area, since the lens has to be stopped down anyway.

    ~Joe

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