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  1. #1
    Reinhold's Avatar
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    Home Made Soft Portrait Lens

    Soft Portrait Lens

    I just finished mounting a soft portrait meniscus lens for my 5x7 Deardorff.
    I'm delighted with the results, it handles like an old 1800's barrel lens.
    And the negative it produces is just like a classic 1800's portrait...

    The lens is a simple meniscus lens of about 300 mm focal length and a 60 mm diameter, giving a maximum aperture of about f5.6.

    This is more than a patch-up collection of paper tube and duct tape.
    The barrel is machined from PVC tubing.
    The lens is seated against a machined stop and is secured with a machined PVC retaining ring.
    It's fixed onto a Masonite lensboard with stainless flat head screws from the backside.
    The next iteration will have a PVC flange so it can be attached to a lensboard from the front with small screws, just like it was done in 1880.

    For the aperture stops, a 1mm wide slot is machined into the barrel into which I drop stops cut from black 4-ply matboard.
    The matboard fits the slot nicely so light leaks are not a problem... if I don't dawdle between pulling the darkslide and taking the picture.
    At first, I draped a black sock over the stop to cut down potential like leakage.
    I'm happy to report that black socks are not required in the subdued light of a typical studio.

    For a shutter, I flip a piece of black matboard across the lens, (I don't use the traditional hat, this is the 21st century, after all...)

    I develop by inspection so each shot results in a good negative regardless of the exposure time which is somewhat imprecise, to be sure.

    The photo of Larry was shot on Arista EDU 100, developed by inspection in Pat Gainers PCT 1+45 for 6-3/4 minutes. Shot it at f8, about 1-1/2 stop smaller than wide open. It's a straight scan of the negative.

    Any interest in something like this?

    Reinhold

    www.classicBWphoto.com
    Attached Thumbnails Attached Thumbnails 308 Meniscus 1.jpg   308 Meniscus 5.jpg   308 Meniscus 3.jpg   Larry @96.jpg  
    Last edited by Reinhold; 02-21-2011 at 05:37 PM. Click to view previous post history.

  2. #2

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    Yeah, very interesting. I'd like to read more, and see some of your images. Thanks for your work.

  3. #3
    nhemann's Avatar
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    Hello Reinhold,
    Interesting piece and thanks for posting. I was wondering if you could recommend any reading material regarding how you select a particular lens diameter and focal length for a particular project. I have been researching making homemade lenses on and off for a while but always ran short on information that didn't quickly ramp up to graduate level optics discussions - and the engineer in me bristles at the idea of just guessing. lol
    Neil

  4. #4
    Reinhold's Avatar
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    Thanks folks,

    Before I post more images, I've got to get ok's from the others...

    Niel;
    Regarding lens selection, I'm working with 5x7, so I wanted a longer focal length in order to keep the subject as far away as possible. I'm not a fan of wide angle lens portraiture. Normal for 5x7 is about 210mm, so the 300mm lens I found is equivalent to a "long normal", a decent choice for starters...

    I also wanted a reasonably fast lens (this is for portraiture, after all), so an aperture of 5.6 or better was my aim point.
    I found a 65mm diameter lens that, when mounted gave me a clear aperture of 60mm and a maximum aperture of f5.0. (300mm fl / 60mm dia = f5.0)

    Using the same formula I cut a variety of Aperture stops, from f6.3, thru f16.
    I liked the f8 aperture best on the ground glass and most of my efforts have been at f8 so far.
    On the ground glass F11 looked a bit too snappy and f16 was even sharper (like those old B&J paper weights).

    In my limited reading on meniscus lens applications, the concave surface faces forward and the aperture stop is as close to the front of the lens as practical. I've got more information squirreled away somewhere, when I find it I'll post it. Unfortunately, much of it isn't graduate level optics either, but it's a start...

    Reinhold

  5. #5
    jp498's Avatar
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    Great project and very interesting!

    Next one, you might try different distances for the aperture slot from the lens. I think that's one the variables in how the aperture works and how it's effective. Spacing that might change one type of aberation or something. I'm no expert either... I've just seen some of the commercial meniscus lenses and they all seem to have different spacings between the aperture and the glass. Things like the kalosat, kodak portrait, p&s semi-achromatic, etc...

  6. #6
    Toffle's Avatar
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    I did essentially the same process to mount a dollar-store magnifying glass on my 8x10, with the resulting lens being 325mm f3.5 and with apertures down to f42. The following photo is typical of its performance. (5x7 paper negative)

    Last edited by Toffle; 02-21-2011 at 08:37 PM. Click to view previous post history.
    Tom, on Point Pelee, Canada

    Ansel Adams had the Zone System... I'm working on the points system. First I points it here, and then I points it there...

    http://tom-overton-images.weebly.com


  7. #7
    Reinhold's Avatar
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    Toffle: great photo.

    I too, play with Dollar Store lenses.
    I have several mounted in plastic barrels with aperture stop slots similar to this one.

    I found that I really like the image projected by a simple meniscus more to my liking for portraiture.

    Some have confused this simple meniscus as a "Petzval" lens.
    Not even close...
    Petzvals are complex lenses which have evolved over the years, as this website illustrates:

    http://www.antiquecameras.net/petzvallens.html

    What's fun about this project is that I'm able to merge photography with my ability to run a lathe and create fun things, such as an easy-to-use camera worthy lens with unique imaging character.

    It's a never-ending voyage of discovery...

    Reinhold

    www.classicBWphoto.com

  8. #8
    pinhole_dreamer's Avatar
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    Gives me an idea about a magnifying glass I saw at Wal-Fart and a box that I saw at Hobby Lobby. *sigh* How many more cameras can a girl make? (I have four pinhole cameras - and some of them are for my ball joint dolls. I just have to make THEM a darkroom now, too.)
    I love the smell of fixer in the morning...It smells like...PHOTOGRAPHY!

    The photo blog has moved...
    I Love Film : by Susan McNutt, the mad photographer

  9. #9
    Toffle's Avatar
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    Quote Originally Posted by Reinhold View Post
    Toffle: great photo.

    I too, play with Dollar Store lenses.
    I have several mounted in plastic barrels with aperture stop slots similar to this one.

    I found that I really like the image projected by a simple meniscus more to my liking for portraiture.

    Some have confused this simple meniscus as a "Petzval" lens.
    Not even close...
    Petzvals are complex lenses which have evolved over the years, as this website illustrates:

    http://www.antiquecameras.net/petzvallens.html

    What's fun about this project is that I'm able to merge photography with my ability to run a lathe and create fun things, such as an easy-to-use camera worthy lens with unique imaging character.

    It's a never-ending voyage of discovery...

    Reinhold

    www.classicBWphoto.com
    I have actually used the articles on that site while messing around with a box of old crown and flint elements and other mismatched bits. I have quite a few assorted elements, but not enough that match up to to anything really useful. I have replicated a sort of "Dallmeyer-Bergheim" and an "adjustable landscape" or two, but without the maths (and a little bit of engineering/manufacturing know-how) it is pretty hit and miss.
    Tom, on Point Pelee, Canada

    Ansel Adams had the Zone System... I'm working on the points system. First I points it here, and then I points it there...

    http://tom-overton-images.weebly.com


  10. #10
    Reinhold's Avatar
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    Ok, here's another portrait using this simple meniscus lens.

    A single diffused reflector flood and a fill in panel.
    f8, 1/2+ second (sorta).
    Arista EDU 100, developed by inspection in Pat Gainer's PCT 1+45.

    Meet "Jim"...

    Reinhold

    www.classicBWphoto.com
    Attached Thumbnails Attached Thumbnails Jim @ 96.jpg  

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