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Thread: DIY Meniscus

  1. #1

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    DIY Meniscus

    All,
    Anyone try their hand at making a meniscus lens ? Judging by the prices that the vintage ones have been going for, the considering that I want some abreviations anyway, I might give it a shot.
    Im not sure if Im going to just get a single element, or an an achromat. Thoughts on this ?

    I've been moving a large hunk of brass around my workbench for over a year, so perhaps this would be a novel application for it. Im looking for something in the 210-300mm range; which I've been able to find lenses quite easily (coated even !) for under $10. These have been around 60mm in diameter. Im not sure if Im going to try my hand at making a revolving aperture wheel, or if I will make some discs (ala imagon).

    One design element that I am not sure of is where to place the aperture ? I THINK it should be spaced 1/2 the focal distance infront of the lens; does that sound right ? Also, would there be any way to figure out coverage before I construct the lens ? I want it to cover 4x5, but at the moment Im just looking for the largest glass I can find, and hoping for the best.

    Thanks !

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    The book Primitive Photography by Alan Greene goes into making some very simple lens based on 19th century methods, including a simple meniscus lens and a classic landscape lens, and including rules of thumb for coverage, stop placement, etc. If I remember right, the achromat seems the way to go as you don't have to adjust after focusing to allow for the difference between "optical focus" and "chemical focus." This may depend on the light sensitivity of the emulsion you're using, though.

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    Terence,
    Great, thanks for your help. Im going to see if I can get a copy of that book, and take it from there.

    Regards,

  4. #4
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    The meniscus lens used in many box cameras has the convex surface towards the film and the aperture maybe 1/6 focal length in front of the lens for best performance. Sometimes, to make the camera more compact, the lens has its concave surface towards the film and the aperture behind the lens. This gives a shorter length to the camera, but has more curvature of field. A google search for landscape lens pointed to a couple of downloadable lens designers. I have no experience with either.

    OSLO-EDU from Sinclair Optics OSLO-EDU

    CODE V from Oprical Research Associates CODE V

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    Jim,
    Excellent ! OSLO-EDU has a linux version ! Im going to mess with this when I return home later this evening.

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    Oslo is a nifty program, but I haven't had much luck with it. I'm fairly dependent on what lens are available from Surplusshed.com, Anchor Optical (Edmund Scientific), etc.

    The landscape lens in the Greene book has the concave side towards the subject. Although much simpler, it looks very similar to the old Darlot landscape lenses, with a small (to my eye) stop at the front of the barrel to cut down on some of the distortion.

    There's one historic photo in the book, I believe taken with a landscape lens, that has the Galli-esque swirly bokeh, and the most amazing look to the in-focus areas. The in-focus areas almost look 3-D, but also make the subjects look like a little diroama. the combination of distortion, bokeh and depth-of-field is what I've been trying to replicate, unsuccessfully.

  7. #7

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    For a non technical DIY type approach to making simple lenses.... take a look at the on-line reprint of my friend's View Camera article

    http://www.siskinphoto.com/magazine/...nsAssembly.pdf

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    Quote Originally Posted by Terence
    ... that has the [COLOR=Red]Galli-esque[/COLOR] swirly bokeh ...
    There you go Jim, when your name becomes a new word you know you have truly made it!

    Nathan

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    All,
    Thanks again for the info...It looks as if I really need to get a copy of that book. As far as the lenses go, I will be doing all of my purchasing from surplus shed as well, so in a way the lens design software is a moot point; but then again if I can get the specs on the glass, I can at least see what it is theoritically able to do.
    The only issue that Im really worried about is coverage. Any thoughts on this ? Im just going out and buying the largest lenses I can find that are in my desired focal range (surplusshed has about 10 lenses that should work, coated too !).

    Tom- interesting article, thanks for the link

  10. #10

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    The irony is that both of the lenses I've bought from Jim are very sharp G-Clarons. My brass cannons have been from other sources.

    I'm still trying to figure out how I can make/adapt something to use with my 28" focal length, brass, portrait lens. A head-shot on 8x10 would require more than three feet of extension. Living in a 750 SF apartment, that would take up half my living room.

    Actually, my favorite swirly bokeh photo is still Kerik's girl surrounded by trees, but I gave Jim the hat-tip as he has been such a promoter of the look.

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