Floating lens

Discussion in 'Medium Format Cameras and Accessories' started by ulysses19, Apr 1, 2007.

  1. ulysses19

    ulysses19 Member

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    Does anyone know how the RZ ProII so called "floating lens" wide angle lenses(50mm+65mm) work, both optically and practically? One focuses and then rotates the front element to correct for distortion? Are they really an improvement over the previous versions of these lenses? Any info would be appreciated. Thanks.

    <todd>
     
  2. Sparky

    Sparky Member

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    If what you're talking about is what I THINK you're talking about... no - not at all. In most designs like this there is a central element or group in the middle of the lens, whose position is shifted forwards or backward depending on focal point to allow for distortion correction. It's 'automatic' - you don't do a thing. Many other manufacturers have similar designs, i.e. Hasselblad's FLE designs...
     
  3. PHOTOTONE

    PHOTOTONE Member

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    The 50mm for the RB-67 I have, has a "floating element" which is supposed to improve definition. Since this type of camera focuses with a built-in bellows, rather than a focusing ring on the lens, you set the "floating element" by first focusing the lens with the knob on the camera, note the distance on the scale on the side of the camera, and then set the ring on the lens to the same setting. Not for quick candids, however I have found that for practical field photography, it doesn't matter much if the lens is set for each distance.
     
  4. Roger Hicks

    Roger Hicks Member

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    That was my recollection of the 50 too (I got rid of it well over a decade ago). There was litte difference in real-world pics as compared with test shots.

    Cheers,

    R.
     
  5. Xmas

    Xmas Member

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    The difference is more visible wide open, on a big print, but it is noe easy to see leave the lens close to the distance you espect, so that you can take a snapshot if you need.

    Noel
     
  6. Steve Smith

    Steve Smith Member

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    Are there two versions of the 50mm for the RB67? I have one which has the front ring as described but as far as I am aware, it is only used to set up the depth of field scales. I know there are other RB/RZ lenses which do have this floating element but I didn't think the 50mm was one of them.
    This could be why it doesn't appear to make much difference to the image.

    I could be completely wrong though!

    Steve.
     
  7. Helen B

    Helen B Member

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    The 40 mm for the SL 66 is similarly available* in both FLE and non-FLE versions, and the FLE's floating element has to be set on the lens for the same reason as for the RB. The floating element has only three positions. Even though the position of the floating element is not critical in most cases, the FLE version is a generally better lens than the non-FLE.

    Best,
    Helen
    *Calling the FLE version 'available' is a bit misleading, unfortunately.
     
  8. Xmas

    Xmas Member

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    Both the 50mm and 65mm for the RB67 circa 1985 had floating elements set by what looks like a depth of field rig at front of lens.

    Noel
     
    Last edited by a moderator: Apr 16, 2007
  9. konakoa

    konakoa Member

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    I have a 65mm for my RZ with the floating element system. Indeed, as Phototone noted it's not a fast system, yet the floating element does make a difference. Noel's suggestion to keep it pre-set is good advice.

    In particular I have some landscape shots where I forgot to set the floating element for infinity -- I was in too big of a hurry to get the shot. When I got home I noticed the floating element was at the minimum focus setting, and when I later printed the negatives they all had soft corners. I never noticed it in the finder, but it sure showed up in the prints! (11x14) Since then I always check it. It usually takes one good goof-up to make somehting a habit eh?
     
  10. Ryuji

    Ryuji Member

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    Floating element is a commonly used technology in modern, large aperture wide angle lens that can focus rather close. I think several 5mm SLR lenses use the same technology, but they are usually (always?) transparent to the user.

    The correction from the floating element has the largest impact when you shoot nearby object at wide open, and the importance diminishes as the subject moves far and the lens gets stopped down.
     
  11. Mike Kovacs

    Mike Kovacs Member

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    Indeed they do. E.g., Nikon calls it CRC "Close Range Correction". My AIS 24/2.8 Nikkor has it and it automatically adjusts with the focus setting. The lens has nice sharp corners even at minimum focus of about 1 foot and at wide apertures. I'm not sure though what would happen if I tried something like using an extension tube or bellows, with the CRC set at infinity. I probably wouldn't notice anything unless I was shooting something flat.

    On medium format, I would expect the gains to be a little smaller, unless you are shooting a lot with wide open apertures. I wish I had an FLE 40mm Distagon for my SL66 rig. I've only seen a couple for sale on ebay ever.