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  1. #1

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    source for simple lens designs?

    i have built some lenses from Allan Greene's book "Primitive Photography"...heck, i built an 8x10 camera from the book too! but for the sake of convenience, i'm more interested in using the lenses with a packard shutter on my 4x5 monorail.

    i've built two, and will probably get around to building the other two described in the book. but...does anyone know of any sources for easy-to-build lenses along these lines?

  2. #2
    Ty G
    If you mean actual lens elements...I sometimes get them from anchor optical. For my purposes, I used acromat.

  3. #3

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    thanks Ty, but i meant sources for designs of the lenses. i've bought elements from Surplus Shed. i just want some guidance on making new lenses (ones that can be cobbled together with elements and pvc pipe, that sort of thing).

  4. #4
    semeuse's Avatar
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    Hey Matt -
    Check out John Evans Exploring Simple Lenses available at alternativephotography.com

    Kris

  5. #5

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    Quote Originally Posted by semeuse View Post
    Hey Matt -
    Check out John Evans Exploring Simple Lenses available at alternativephotography.com

    Kris
    Yep
    Its an E-book containing around 1500 pages or so. I find it very good with plenty of designs covering fomats from 24X36 to 6X7. There are sample photos and how to chapters and its cheap too. I think you can easily convert the designs to cover 4X5
    Kind regards
    Søren
    Send from my Electronic Data Management Device using TWOFingerTexting

    Technology distinquishable from magic is insufficiently developed

    Søren Nielsen
    Denmark

  6. #6

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    g'day Matt

    i've made many lenses from magnifying glasses and 90mm plastic water pipe

    check out my various posts on the subject

    i started by making a 5x8 dark slide out of MDF, then a camera to fit, then an 8x10 dark slide and a camera to fit, then i got obssesed

    i have now made 9 cameras, 1-5x4, 1-5x7, 3-5x8, 3-8x10, 1-11x14 and about 20 DSs

    plz ask if you'd like more info

    Ray
    Last edited by Ray Heath; 12-04-2007 at 03:53 PM. Click to view previous post history.

  7. #7

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    Soeren and semeuse: thanks very much for the recommendation! i'm not usually a fan of doing a lot of reading at the computer, but 1500 pages...that sounds like a good thing to have. perhaps i'll get one for christmas.

    of course i was looking for something free and immediate online.

    Ray: are most of your lenses single-element types then? also, what do you use for a shutter? (bowler hat?). thanks, and i'll check some of your other posts.

    -matt

  8. #8

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    I'd be interested in this kind of thing too. If all else fails I'll buy the e-book

    I've been playing with diopters lately after serendipitously discovering that a Nikon +2 eyepiece diopter alone covered 4x5 and 8x10 as a 320mm f/16 to f/22. I ordered a +3 diopter for a couple of bucks and it turns out that it's about a 150-200mm lens. When I put the two together back to back the focal length becomes quite short (75-90mm?) and the coverage shrinks down to about 4x5 or less. I'd assume this arrangement is vaguely related to the asymmetric turner reich triple convertible I use.

    I don't really understand the optics here and I'd like to. Optimal spacing, focal lengths (I know there's a pretty simple compound lens focal length formula, but I'm not sure it applies), etc.

    I haven't done anything I'm proud to post with the diopters yet, but here are ugly examples / tests from 8x10:
    http://ashphotography.ca/zenphoto/al.../homesweet.jpg
    http://ashphotography.ca/zenphoto/al.../whymytree.jpg
    The universe is a haunted house. -Coil
    .

  9. #9

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    Walter, to get from a lens' strength in diopters to its focal length (or vice versa), use the formula published here: http://hyperphysics.phy-astr.gsu.edu...pt/foclen.html

  10. #10

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    G’day Matt

    All my lenses are simple, single element designs made by mounting one magnifying glass in 90mm plastic water pipe fittings. Magnifying glasses are readily available and cheap. Pipe fittings are readily available at hardware stores. I use screw on pipe caps, screw in collars and push on pipe caps.

    ‘Simple’ lenses give ‘bad’ spherical aberrations which cause the image to be sharp in the centre and blurred around the edge, use of small apertures, f45-f90, cause the image to sharpen dramatically (see attached fence posts image). I like the blur and the less than perfect image quality.

    Apertures are holes cut or punched into discs made from thin black plastic sheet such as used for covers on visual art diaries. The disc is held in place with Blu Tac, this allows me to compose without the aperture then insert it for the exposure.

    Shutter is a lens cap made from a 90mm push on pipe cap. Shutter speeds of less than one second are not possible, this no restriction when using FB paper for negs as the exposure is often more than 5 seconds. For film or brighter conditions I may need to use ND filters or very small apertures.

    I have also experimented with dioptre filters. My initial experiments were with dioptres mounted in 90mm pipe fittings (see old shop image). I soon realised the diameter of the filter mounts would not allow extreme wide angle coverage.

    I neither enjoy nor understand maths so I kept the necessary calculations simple and relevant.

    To calculate focal length from dioptre number;
    fl=1000 divided by D

    To measure focal length of a simple lens or magnifying glass;
    fl=distance from centre of lens to film plane when lens is focused at infinity

    To calculate effective aperture, also called “Relative Aperture” because it is relative to the focal length of the lens in use;
    f=fl divided by diameter of aperture

    To calculate effective coverage as related to 35mm lenses;
    fl divided by diagonal of format, multiplied by 50

    e.g. what focal length on a 35mm camera will give the same angle of view as a 235mm lens on an 8x10 camera;
    235 divided by 310, times 50=37.9mm lens

    Ray
    Last edited by Ray Heath; 12-04-2007 at 03:53 PM. Click to view previous post history.

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