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Thread: Floating lens

  1. #1

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    Floating lens

    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. #2
    Sparky's Avatar
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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. #3

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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. #4

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    Quote Originally Posted by PHOTOTONE View Post
    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.
    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. #5

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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

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    Steve Smith's Avatar
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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. #7
    Helen B's Avatar
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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. #8

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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 Xmas; 04-16-2007 at 12:29 PM. Click to view previous post history.

  9. #9

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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. #10

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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.

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