Mamiya RB67 150mm Soft Focus with 3 diffusion disks

Discussion in '[Classifieds] Want to Buy' started by Perry Way, Jan 27, 2012.

  1. Perry Way

    Perry Way Member

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    Have a wedding to shoot that requires this lens and I don't have it and I've always wanted it.

    Must be perfect/near perfect glass and must include the 3 diffusion disks!
     
  2. epatsellis

    epatsellis Member

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    Perry,
    KEH usually has one or two BGN grade 150s for ~$75, and it will have a 6 month warranty as well. Try to spend some time with it before you shoot, as the SF takes a bit getting used to, the best looking SF is without any discs, and shot close to wide open.
     
  3. markbarendt

    markbarendt Subscriber

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    I got mine from KEH as bargain grade and it is great.

    Focus can be a challenge so I ended up getting myself a rangefinder spot split image focusing screen, seems to help.
     
  4. jnanian

    jnanian Advertiser Advertiser

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    i am curious about how you folks focus with this lens ..
    i have the instructions that came with my portrait veritar
    and it suggests the user stop down to f8, focus, then open it up
    for the soft effect. with the lens perry is asking about
    is it possible to stop down, seeing it is an slr type camera, how do you stop down
    and focus ... do you have to use the DOF preview button ?

    sorry to hijack your thread perry --
    good luck with the wedding!

    john
     
  5. Marc B.

    Marc B. Member

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  6. Perry Way

    Perry Way Member

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    Thanks for the ideas guys!

    About the disks, from what I've read, the disks main purpose is to adjust the f-stop to dimmer. When shooting with lighting, what if you can't make anything work wide open at f4? Then pop in a disk, go down to f5.6 and f8 and f16. That's the purpose of them.

    From what I can figure out on my own, the diffusion disks also add a zone sieve effect to the optics so as they limit the light going through the lens they add their own diffusion which ups the soft focus ability.

    I intuit these disks being highly necessary!

    Oh, and John, you can stop down a Mamiya RB67 lens (I just don't recall at the moment how) but it's a several step process IIRC...

    I've got a lens I'm bidding on at the moment. Going to let that play out first since I bid a high amount and haven't been outbid yet.
     
  7. epatsellis

    epatsellis Member

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    wrt to the discs, I thought so too, until I actually had the lens in my hand, then I realized that I much prefer the soft focus effect without the strainer looking OOF highlights. ND filters preserve the creamy smoothness that this lens produces in OOF areas.

    Stopping down an RB lens is very, very difficult....(not really), there is a DOF preview tab on the side of the lens, push it down and "voila", stopped down.

    Quite frankly, I'd avoid ebay at all costs with RB lenses especially. While they are very durable and reliable lenses, they are all getting a little long in the tooth, and they all need service at some time, at least buying from KEH, you know that anything that crops up in the next 6 months will be taken care of. BGN grade will save you a fortune if you are more concerned with functionality over appearance, BGN should have no marks on the glass.
     
  8. Ian C

    Ian C Member

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    The purpose of the diffusion discs is to alter the image further than is the case without them. Each of the holes in the diffusion discs acts like a pinhole adding its diffraction to the overall image.

    The 2-element Rodenstock Imagon was an earlier soft focus portrait lens that used diffraction discs to project a soft image onto a sharp core image.

    The diffraction disks of the Mamiya 150mm RB67 and 180mm RZ67 lenses work in the same way. Their purpose is not to alter exposure, although they do alter it since the solid areas of each disc pass no light.

    Here is Rodenstock’s explanation of the function of the diffraction disks in the Imagon lens:

    “High-quality lenses are normally expected to yield sharp, crisp images. For some applications, however—for example in portrait shots—a softer luminous rendering is preferred over faithful detail sharpness.

    It does not produce the blurred images typical for incorrect focusing or poor quality lenses. It rather overlays a clearly defined image core with delicate diffusion controlled by adjustable push-on perforated diaphragms. By spreading highlight outlines into the shadows, the Imagon softens the hard definition, yielding portrait or landscape effects that range from a slightly flattering rendering to dreamy, romantic moods.”


    The Mamiya SF lenses are a more refined design that uses intentional spherical aberration to project a soft image onto the core image produced by the accurately shaped central region of the lens. Mamiya says that the spherical aberration designed into the outer part of the lens is completely blocked at apertures of f/8 or smaller making this lens equally sharp to its regular 6-element lenses of the same focal length.

    The large central hole in each disc is sized so that stopping down to f/8 or smaller eliminates the effect of the disk.
     
  9. Perry Way

    Perry Way Member

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    I've seen photographs side by side taken with no discs and then with discs. I want the additional diffusion effect by the discs. That's what I'm seeking for the most! Have you ever taken a photograph with a zone plate or zone sieve? They are amazingly beautiful if you have the lighting and contrast controlled real well.

    Yeah you got me on that! I get jumbled in the head sometimes.. something similar to dyslexia. I was mentally reciting the steps that it takes to do mirror-up photography with the RB67.
     
  10. Perry Way

    Perry Way Member

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    Regarding the comments as to the discs.... Here's two of my photos, same camera, same scene, same day, same light, one is pinhole the other is zone plate, both taken about 1 minute of each other.

    The extra diffusion you see in the zone plate image is similar to what happens with the discs on the Mamiya RB67 150mm SF lens.

    Pinhole:
    4861842453_ff1a1196a1.jpg

    Zone Plate:
    4861842333_ac4b16c904.jpg
     
  11. epatsellis

    epatsellis Member

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    I find it's a matter of preference, most of my work with the RB was tabletop commercial photography over the last 25+ years, the OOF highlights had the sieve pattern in them, exactly the same as the Imagon does. (both of which I've used frequently over my career) Aesthetically, I find it distracting.

    While acceptable when you are shooting landscape or people and can tweak camera positioning and the like, in a commercial setting where you are shooting to a layout, and the AD want's an OOF background, when specular highlights are existent, it really can look bad. Even now, when shooting with a Dicomed scan back, I tend to avoid using the sieves and reach for an ND or decrease my line time (same as increasing shutter speed) if needed.

    When you get the lens, from wherever, try it with and without sieves, wide open or close to it, and let me know, I'd be interested to know your thoughts.
     
  12. markbarendt

    markbarendt Subscriber

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    Yes stop down to f8 and there's a DOF preview lever that stays put until you bring it back.
     
  13. markbarendt

    markbarendt Subscriber

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    Actually the disks are #1 (5), #2 (5.6), #3 (6.3). At f8 or smaller the lens is fully normal, the soft effect is gone.

    I believe you are right about using the disks to stop down a bit, they do modify, but also help retain the effect, more than simply stopping down directly to the equivalent stop.

    You'll be wanting some slow film. :wink:
     
  14. Perry Way

    Perry Way Member

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    I found a suitable lens. Actually I found several but I lost auctions until I found one listed as perfect and it had a Buy-it Now so I bought it 10 minutes ago rather than roll the dice again. Anyway this one came from a photographer, so I feel much better buying this one. Thanks to those who posted here. It's incredible the differences that exist between many photographers in one setting.

    Oh, and I got it for $187 shipped. Not a bad price at all for perfect, with front/rear cap, lens hood and filter.