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Thread: Teach me about Lens Design

  1. #31

    Join Date
    Feb 2016
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    Netherlands
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    141

    Re: Teach me about Lens Design

    Making the board from 3mm birch ply, with a fretsawed-and-sanded hole would be quick and easy, and both stronger and more reliable than mattboard. If there aren't enough threads to get through 3mm of wood you can always put a 1mm aluminium mounting plate on the lens/shutter, then bolt that to the ply board. These sorts of materials are available in any model-making outlet or hobby-shop.

  2. #32

    Join Date
    Apr 2020
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    Washington, DC
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    85

    Re: Teach me about Lens Design

    Quote Originally Posted by Bernice Loui View Post
    Do step drill bits go that large, think it was 57mm?
    Yes, I bought one on Amazon that goes to 2 3/8" = 60mm. The 2 1/16 size (= 56mm) should work with a bit of sanding.

  3. #33

    Join Date
    May 2015
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    SooooCal/LA USA
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    2,046

    Re: Teach me about Lens Design

    I usually make lensboards out of hobby basswood... To build thickness, I layer pieces with grain layers crossing for best stiffness while staying very flat... Easy to cut with utility knife, sand, and cut holes into...

    Adjustable auger bits work good for smaller holes (in a drill press, or soft enough by hand power), or even cheap hole saw sets for over 2 1/4" holes... Even poking enough small slits into the basswood with an Xacto knife will allow hole to emerge...

    My fave hole maker for wood boards is a circle template attachment for a router... Makes a very nice hole in 1/16" increments... Mine goes from about 1/2" to over 6" diameter... And can make stepped holes if carefully planned...

    Steve K

  4. #34

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    Apr 2020
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    Washington, DC
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    85

    Re: Teach me about Lens Design

    I drilled a 57mm hole with a step drill bit. Wasn't easy and I wouldn't recommend using a step drill bit, but I made it work. Its a bit off-center but I can use the camera movements to correct that.

    Next: test photos!

    Tessar_150

  5. #35

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    Apr 2020
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    Washington, DC
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    Re: Teach me about Lens Design

    Also, I bought a cheap 52mm filter, removed the glass, put it "inverted" over lens (perfect fit!) and secured the filter ring with electrical tape to the lens barrel. Now the lens has a filter thread and I can screw in 52mm ND filters (inverted) to use the lens wide open. Clever, huh?

    Tessar_150_2

  6. #36

    Join Date
    Sep 2007
    Location
    AZ
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    4,375

    Re: Teach me about Lens Design

    Quote Originally Posted by giganova View Post
    ... more modern lenses way too sharp and clinical. What I am after is a more vintage look, moderately sharp in the middle, with a drop-off in image quality as you go further from the optical axis, a tiny DOF ... Get a vintage brass lens, mount a Packard Shutter behind it, use it wide open and use ND filters to regulate exposure? Maybe a triplet or an old Tessar?
    I didn't see this the past few days, but to me, if you want a fairly assertive "old" look, you have to use a fairly old or uncorrected type. Your example shots are looking nice, but very sharp and just some secular highlights in the background out of focus area. Any lens can do that.

    If you are looking for fall off within the focal plane, vs behind, I'd consider a Petzval to get more of that look. It's a little hard to get one that will cover a 4x5 well and still fit a lensboard, but it can be done. This is a shot I did on 4x5 with a Cox petzval. Click for larger to see DOF.



    Many today are getting quasi-petzval looks with very fast or very poor lenses. This cine lens I like on m4/3 is probably a petzval type, and again shows the look. If you don't like swirl, just get a slightly longer lens, if you can fit it on the board.


  7. #37

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    Apr 2020
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    Washington, DC
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    85

    Re: Teach me about Lens Design

    Thanks, Garrett! Your image of the chair is pretty extreme. Below are two pictures I took with a single-coated Schneider 150/265 convertible and rear group removed at full aperture. Maybe not the best example because almost everything is at infinity, but you can see tons of aberration/coma (?) except in the middle. I want to go further than that, somewhere between your and my picture.

    Coveys_Landing_1_2_2000pix

    Hillsboro_Landing_1_3_2000pix

  8. #38

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    Apr 2020
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    Re: Teach me about Lens Design

    First photo taken with the 1930s Zeiss Tessar 150mm f/3.5 at full aperture with a 4-stop ND filter. Lovely low-contrast, soft, but sharp lens.

    Thank you all for the recommendations!

    Zeiss_Tessar_150_2_2000pix

  9. #39

    Join Date
    Jul 2008
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    1,827

    Re: Teach me about Lens Design

    Excellent result


    Bernice


    Quote Originally Posted by giganova View Post
    First photo taken with the 1930s Zeiss Tessar 150mm f/3.5 at full aperture with a 4-stop ND filter. Lovely low-contrast, soft, but sharp lens.

    Thank you all for the recommendations!

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