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  1. #31
    Luseboy's Avatar
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    Quote Originally Posted by Reinhold View Post
    The RB-67 has a bayonet mount and a bellows bellows focus system, but lacks a focal plane shutter.

    That didn't stop me from machining an acetal bayonet ring to which I mounted an PVC tubular barrel into which I installed a Meniscus lens.

    Of course, timing is "iffy", since I use the Top Hat Shutter system.
    It works.
    Very nicely.
    Take a look...

    Reinhold

    www.classicBWphoto.com
    That has some nice results it seems. So two questions for you: When I tried making a single meniscus for my 4x5, I didn't have enough bellows draw to focus it at infinity. I'm assuming that the rb67 has less bellow draw than my cambo, so how did you make it work? And number 2: how do you figure out what your f-stop is? trial and error? comparison with other lenses with known f-stops? is there a measurment you can take? I really want to figure this out...

  2. #32
    Reinhold's Avatar
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    Austin,

    For my RB, I used a 125 mm meniscus lens.

    If you didn't have enough bellows draw with your close-up lens, it was probably a + 2 lens.
    A +2 lens has a 500 mm focal length. (You'd need 20" of bellows just to focus at infinity)
    A +4 lens has a 250mm focal length, and would probably work on your Cambo.
    (Depending on how close you want to focus)

    f-stop is simply the focal length of the lens divided by the diameter of the lens opening.

    I now enclose a simple "Tips on using soft focus meniscus lens" page with my lenses.
    If you'd like, I'll PM a copy to you...

    Reinhold

    www.classicBWphoto.com

  3. #33
    Luseboy's Avatar
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    Quote Originally Posted by Reinhold View Post
    Austin,

    For my RB, I used a 125 mm meniscus lens.

    If you didn't have enough bellows draw with your close-up lens, it was probably a + 2 lens.
    A +2 lens has a 500 mm focal length. (You'd need 20" of bellows just to focus at infinity)
    A +4 lens has a 250mm focal length, and would probably work on your Cambo.
    (Depending on how close you want to focus)

    f-stop is simply the focal length of the lens divided by the diameter of the lens opening.

    I now enclose a simple "Tips on using soft focus meniscus lens" page with my lenses.
    If you'd like, I'll PM a copy to you...

    Reinhold

    www.classicBWphoto.com
    yes it was a +2. Well i will try and pick up a +4 soon, hopefully that will work. And thank you for the information! 500 is definitley too long for my cambo haha. But I will keep the +2, so i can use it one day when i get an 8x10. For now though, i am sticking with the 4x5. I would very much like a copy of that, if it's not too much trouble! Thanks!
    oh and how do i figure out the focal length with a random element?

  4. #34

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    I have a big box of assorted lenses just for optical experiments and building "funky lenses"... most are from old 35mm-SLR lenses, that were broken beyond repair. They mostly get used with 35mm film, but a few are good for larger formats. One cheap 200mm/4 lens gave me the front lens with about f=400mm and and an achromat (two elements glued together) with f=200mm. Both are either very soft LF-lenses (covering 8x10 is no problem, though the camera for that is just a cardboard box) or close-up lenses for Kowa Six lenses. I never got the hang of the "hat-shutter", though... Having the small apertures necessary for slow shutter speeds gives too much DoF and sharpness for my taste.

  5. #35
    Steve Smith's Avatar
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    Quote Originally Posted by Rick A View Post
    My faves are 6x9 or 6x6 lenses(80-100mm). For some reason, I'm fascinated with the port-hole look of the image(vignetting).
    I was recently given a Kodak Senior Six-16 camera with a 123mm lens (I think). I am converting the camera to 120 film and whilst I had the lens removed, I tried it on my Speed graphic and was surprised to see full coverage. I have also had full coverage of 5x4 with a Kodak 105mm lens from a 6x9 camera.

    It's also fun to play around mixing up front and rear cells which weren't meant to go with each other.


    Steve.

  6. #36
    Reinhold's Avatar
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    You can get a reasonably accurate measure of the focal length of a lens by temporarily taping it to a blank lensboard on your 4x5 camera.
    If you don't have a lensboard, hack one out of a piece of stiff paperboard.

    Focus on an object far away (close to infinity), and measure the distance from the lens to the ground glass.
    That's the focal length.

    Reinhold

    www.classicBWphoto.com

  7. #37
    Terrence Brennan's Avatar
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    I use an old magnifying glass as a lens on my venerable 4x5 Graphic View, with a focal length of about 95mm/3.75-inches. It has a maximum aperture of about f/2.8, and I have a set of home made diaphragms which go down to f/48.

    It flares like crazy, and I have found that when working outdoors, the best course is to use a lens shade, as well as a #16 or #25 filter to "tame" the sky a bit.

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