is floating element/close range correction on wide-angle lenses worth it?

Discussion in '35mm Cameras and Accessories' started by darinwc, Feb 4, 2010.

  1. darinwc

    darinwc Subscriber

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    Some wide-angle lenses like the olympus 21mm f2 were designed with floating elements.

    I thought that by using lenses with such great depth of field, you could get just about everything in focus.
    Do you think it is really necessary for wide-angle lenses?
     
  2. thisismyname09

    thisismyname09 Member

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    I don't think the purpose of floating elements is to get more depth of field, its to correct for other sorts of aberrations that reduce sharpness when you focus up close. When lenses are designed they're, for the most part, designed with focus at infinity in mind. When focusing *really* close, you lose sharpness, not depth of field, because the lens was not designed to perform at such distances. Macro and copy lenses are designed with close focus in mind, and thus don't function well at infinity. Lenses with floating elements are designed to perform well at all distances, so to answer your question, they are necessary if you need the utmost sharpness and work at a wide variety of distances.
     
  3. AgX

    AgX Member

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    Why do these lenses have a focussing barrel? Even large aperture fish-eye lenses have a focussing barrel.

    `In focus´ is a relative term. For best results a lens should be able to be focussed. And then, as said above, one can design additional means to enhance image quality at focus distances off the range which is considered the main range.
     
  4. Sirius Glass

    Sirius Glass Subscriber

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    Use the Zeiss Biogon lenses, like the Hasselblad SWC. :D

    Fish-eye lenses are supposed to have barreling. That is part of the "charm".

    Steve
     
  5. lxdude

    lxdude Member

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    I've always found my macros (EBC Fujinon 55mm f/3.5, Nikkor I.C. 55mm f/3.5, SMC Pentax 100mm f/4, Bronica PE 105mm f/4.5) to work quite well at infinity. Perhaps part of that is the high degree of resolution and correction they have to begin with.
     
  6. Mike1234

    Mike1234 Inactive

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    I removed the floating element from my 55mm Micro Nikkor and dropped it in water. It sank!! So much for truth in advertising...
     
  7. Q.G.

    Q.G. Inactive

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    You should have dropped the floating element in the water.
    Not the 55 mm Mikro Nikkor.

    Certainly not when you first remove the floating element from the 55 mm Mikro Nikkor.
    What were you thinking ... ?!
     
  8. keithwms

    keithwms Member

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    Yes, but only if you truly need corner sharpness at a wide aperture.

    If your subject is centered and the rest of the frame is outside the depth of field then it won't amount to a hill of beans.

    If you stop down extensively (well into the diffraction) then it also will not amount to a['nother, separate] hill of beans.

    So, those are two prominent hills of beans that you must steer between if you aim to get the most out of the floating element lenses.

    Ha, maybe we need FDA-like disclaimers on the lenses....
     
  9. AgX

    AgX Member

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    I should have added that retro-focus wide-angle lenses are much more prone to reduction of image quality at different focussing distance (typically short distances) than standard wide-angle constructions.

    That is why there are no floating elements used in those.
     
  10. lxdude

    lxdude Member

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    The floating element is actually heavier than water, so you have to place it carefully on the water to make it float.
    Out in space, they're all floating elements.
     
  11. lxdude

    lxdude Member

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    I hate it when I get beans in my lenses. Interferes with the floating elements.
     
  12. lxdude

    lxdude Member

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    :D
     
  13. lxdude

    lxdude Member

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    That's elementary.
    Maybe he wanted to make it lighter? Of course, painting it white would accomplish that.
     
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  15. Mike1234

    Mike1234 Inactive

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    To all who replied to my floating element test: I did drop the floating element in the water... not the lens. As I said before it sank. However, I now realize my mistake. I should have used heavy water.
     
  16. darinwc

    darinwc Subscriber

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    UUUUUGG! FACE+PALM
     
  17. lxdude

    lxdude Member

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    Ah! I now have a nu clear understanding.
     
  18. Q.G.

    Q.G. Inactive

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    Ah, yes!
    A common, because easy to make, mistake.
    Someone should have warned you in advance.

    But what did you say before it sank?
     
    Last edited by a moderator: Feb 5, 2010
  19. darinwc

    darinwc Subscriber

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    I think my advance is stuck. It wont move past 24.
    And how do I get into play mode?
     
  20. Q.G.

    Q.G. Inactive

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    Press "Play".
    Should be near "Pause", and in between "Fast forward" and "Rewind".
    Don't touch "Rec" though.
     
  21. Mike1234

    Mike1234 Inactive

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    I chanted (not said), "Abbra cadabra... FLOAT, you magical bit of optical wonder"!! Maybe I didn't use the correct chant?!
     
  22. Q.G.

    Q.G. Inactive

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    Maybe... yes...
    But i still suspect your previous hunch (the non-obese water one) is nearer the mark.

    Or... maybe it wasn't a floating element (it didn't, right?), but a flouting element?
    What that would entail exactly, i don't know. Yet. But how about it?
     
  23. Someonenameddavid

    Someonenameddavid Member

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    You should have gone OM




    :smile:D)
     
  24. lxdude

    lxdude Member

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    With a Nikkor?
     
  25. Mike1234

    Mike1234 Inactive

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    ^^^^ I think he meant o-o-h-h-m-m-m-m-m.......... o-o-h-h-m-m-m-m-m.......... o-o-h-h-m-m-m-m-m.......... o-o-h-h-m-m-m-m-m..........

    Then again, he was probably making a pun. :D
     
  26. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    Ahem....getting back to the original topic, I agree with this. Wide lenses on SLRs are already at a disadvantage, so anything to improve them is a good thing. Another fault of wide retrofocus lenses at close subject distances can be significant barrel/pincushion distortion, even if they are close to perfectly rectilinear at, say 6 feet or infinity.