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  1. #1

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    'Splain to me Lucy.. Mamiya Floating Element Lens

    Ok, after reading a number of threads about the floating elements in several Mamiya lens, I went back and looked at my collection. So that's what that ring does! Both 50mm and 65mm have floating elements. Now what does that do? It might explain why my 50mm shots have not been tack sharp. I have mostly used the 50 on 135 film that I run through a 220 back on modified spools. While I like the images a 36x68 negative give, they have not seemed that sharp. The 65 I shoot with a lot in 120 and haven't seen any image degradation, perhaps I was lucky and it's always been set on infinity?

    So what's the story? Why and how do you use this feature and does it truly help in sharpness issues with these lens?

    tim in san jose
    Last edited by k_jupiter; 12-27-2008 at 08:02 PM. Click to view previous post history. Reason: speling of corse
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  2. #2
    Lopaka's Avatar
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    If you look at the floating element ring that rotates, directly opposite the distance scale on the rotating ring, there is what looks like a depth of field scale, with the widest apereture of the lens in the center. After you focus, you rotate the ring to point the distance on which you are focused at the center of the scale. After doing this, you re-check your focus. The theory behind this is that the floating element maximizes the sharpness of the lens for the specific distance on which you are focused. The bonus is, this scale also should give you an idea of the approx depth of field at that distance for various f-stops.

    Bob
    "I always take a camera, That way I never have to say 'Gee, look at that - I wish I had a camera'" -Joe Clark, H.B.S.S.

  3. #3
    Alex Bishop-Thorpe's Avatar
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    Many lenses incorporate floating elements, but since a lot of them work on a focus helical (that dingus you twist to focus), it's adjusted for mechanically. Since we focus via bellows on the RB67, we have to adjust it manually...Which I totally overlooked the one time I borrowed the 50mm.
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  4. #4
    David Brown's Avatar
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    Quote Originally Posted by k_jupiter View Post
    It might explain why my 50mm shots have not been tack sharp. I have mostly used the 50 on 135 film that I run through a 220 back on modified spools. While I like the images a 36x68 negative give, they have not seemed that sharp.
    Tim:

    Try the 50 on some 120 film and see if the negs are the same. I would suspect that the 35mm film might not be flat and/or exactly in the film plane with the setup you describe. Just a thought ...

    Also, try using the floating element on the 50.

  5. #5
    keithwms's Avatar
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    You *must* use the floating element on the 50 to have optimal corner sharpness! This will be especially obvious with the 6x8 back. It may not matter one iota for the 645 back.

    Unfortunately there is the confusion that several mamiya lenses have a ring that looks like a floating element adjuster but it's just a DOF ring.
    "Only dead fish follow the stream"

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  6. #6
    Lopaka's Avatar
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    Quote Originally Posted by keithwms View Post
    Unfortunately there is the confusion that several mamiya lenses have a ring that looks like a floating element adjuster but it's just a DOF ring.
    Correct. Those that are floating element will have words like 'Floating System' on the ring.

    Bob
    "I always take a camera, That way I never have to say 'Gee, look at that - I wish I had a camera'" -Joe Clark, H.B.S.S.

  7. #7

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    Quote Originally Posted by Lopaka View Post
    Correct. Those that are floating element will have words like 'Floating System' on the ring.

    Bob
    Hmmm, no "Floating System" on these lens, but when you move the ring, the lens elements turn inside. On each of my other rb67 lens (except the 150SF) there is a DOF ring that does nothing except give standard DOF info.


    tim
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  8. #8
    keithwms's Avatar
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    Tim, I think the rb ones don't necessarily have "floating element" inscribed on them. I have seen some that did and some that didn't. It's an unfortunate point of confusion that Mamiya brought upon their clients, and I suspect that it has led to some unfortunate reviews.

    Well, this is the [small] price you pay for bellows focusing instead of helicoidal. If the mamiya 6x7 systems were based on helicoidal then it'd be possible to have auto FE adjustment like you have in the Nikon wides ("CRC"). Oh well, one simply has to take the time to research and learn how to get the best performance.
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  9. #9
    chriscrawfordphoto's Avatar
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    Quote Originally Posted by keithwms View Post
    Tim, I think the rb ones don't necessarily have "floating element" inscribed on them. I have seen some that did and some that didn't. It's an unfortunate point of confusion that Mamiya brought upon their clients, and I suspect that it has led to some unfortunate reviews.

    Well, this is the [small] price you pay for bellows focusing instead of helicoidal. If the mamiya 6x7 systems were based on helicoidal then it'd be possible to have auto FE adjustment like you have in the Nikon wides ("CRC"). Oh well, one simply has to take the time to research and learn how to get the best performance.
    What's funny is that Hasselblad's floating element lenses, the 40mm and 50mm FLE Distagons, have helical focusing but still have a second ring for the floating elements. A real pain, since the other manufacturers ho use helical focusing have the floating elements automatically adjust as you focus.
    Chris Crawford
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  10. #10

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    Quote Originally Posted by chriscrawfordphoto View Post
    A real pain, since the other manufacturers ho use helical focusing have [...]
    Not only other manufacturers. Other FLE lenses for Hasselblad have the floating element moved by the focussing helicoid too.

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