Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,952   Posts: 1,522,728   Online: 872
      
Page 1 of 4 1234 LastLast
Results 1 to 10 of 36
  1. #1
    darinwc's Avatar
    Join Date
    Dec 2003
    Location
    Sacramento, CA
    Shooter
    35mm
    Posts
    2,038
    Images
    157

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

    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. #2

    Join Date
    Mar 2009
    Shooter
    Medium Format
    Posts
    420
    Images
    3
    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. #3
    AgX
    AgX is offline

    Join Date
    Apr 2007
    Location
    Germany
    Shooter
    Multi Format
    Posts
    8,346
    Quote Originally Posted by darinwc View Post
    I thought that by using lenses with such great depth of field, you could get just about everything in focus.
    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. #4
    Sirius Glass's Avatar
    Join Date
    Jan 2007
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    13,009
    Quote Originally Posted by AgX View Post
    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.
    Use the Zeiss Biogon lenses, like the Hasselblad SWC.

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

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  5. #5
    lxdude's Avatar
    Join Date
    Apr 2009
    Location
    Redlands, So. Calif.
    Shooter
    Multi Format
    Posts
    6,582
    Quote Originally Posted by thisismyname09 View Post
    Macro and copy lenses are designed with close focus in mind, and thus don't function well at infinity.
    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. #6

    Join Date
    Jul 2009
    Location
    South Texas, USA
    Shooter
    4x5 Format
    Posts
    1,885
    I removed the floating element from my 55mm Micro Nikkor and dropped it in water. It sank!! So much for truth in advertising...

  7. #7

    Join Date
    Jul 2007
    Location
    Netherlands
    Shooter
    Medium Format
    Posts
    5,686
    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. #8
    keithwms's Avatar
    Join Date
    Oct 2006
    Location
    Charlottesville, Virginia
    Shooter
    Multi Format
    Posts
    6,079
    Blog Entries
    20
    Images
    129
    Quote Originally Posted by darinwc View Post
    Do you think it is really necessary for wide-angle lenses?
    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.

    Quote Originally Posted by Mike1234 View Post
    I removed the floating element from my 55mm Micro Nikkor and dropped it in water. It sank!! So much for truth in advertising...
    Ha, maybe we need FDA-like disclaimers on the lenses....
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  9. #9
    AgX
    AgX is offline

    Join Date
    Apr 2007
    Location
    Germany
    Shooter
    Multi Format
    Posts
    8,346
    Quote Originally Posted by AgX View Post
    `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.

    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. #10
    lxdude's Avatar
    Join Date
    Apr 2009
    Location
    Redlands, So. Calif.
    Shooter
    Multi Format
    Posts
    6,582
    Quote Originally Posted by Q.G. View Post
    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 ... ?!
    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.

Page 1 of 4 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin