Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,913   Posts: 1,521,697   Online: 1052
      
Results 1 to 6 of 6
  1. #1
    Vincent Brady's Avatar
    Join Date
    Mar 2008
    Location
    Co. Kildare - Ireland
    Shooter
    35mm
    Posts
    1,995
    Images
    168

    f stop for max. sharpness on Xpan

    I came across a statement today saying the best f stop for max sharpness when using the XPAN was f8 and not f16 or f22. Can this be true or should I just test it out for myself.

    Cheers
    TEX

  2. #2
    David A. Goldfarb's Avatar
    Join Date
    Sep 2002
    Location
    Honolulu, Hawai'i
    Shooter
    Large Format
    Posts
    17,159
    Images
    20
    It probably depends on the lens, but I suspect it would be around f:8-11 for that format. Stopping down further with the wider lenses should give more even illumination in the corners.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  3. #3
    keithwms's Avatar
    Join Date
    Oct 2006
    Location
    Charlottesville, Virginia
    Shooter
    Multi Format
    Posts
    6,079
    Blog Entries
    20
    Images
    129
    Yep, f/16 is going to be diffraction softened already. f/8 or f/11 sounds reasonable for a typical 35mm RF lens. But try it for yourself!
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  4. #4

    Join Date
    Feb 2009
    Shooter
    Med. Format Pan
    Posts
    8
    As a (perhaps too) general rule, maximum sharpness for a lens is somewhere between 2 and 3 stops below wide open (thus, the f4 45mm Xpan will be at its sharpest around f8-f11).

    As Keith has mentioned, diffraction will probably set in around f16. Mind you, it will be so insignificant at f16 and on such a small format to be almost undetectable at f16 and probably even at f22.

    Also, the untrained eye will see a greater DOF as sharpness, so you should not fear shooting at f22. But, as Keith (again) mentioned, try it yourself. Use a 10x loupe to have a look at 2 scenes shot at different setting and see if you can tell the difference, and if you can, is this difference a show stopper?

    Lachlan.

  5. #5
    keithwms's Avatar
    Join Date
    Oct 2006
    Location
    Charlottesville, Virginia
    Shooter
    Multi Format
    Posts
    6,079
    Blog Entries
    20
    Images
    129
    There is one article by Ken Rockwell, fortunately absent his usual nonsense, that explains all this quite well....

    http://www.kenrockwell.com/tech/focus.htm

    Now, I happen to think that judicious use of DOF is far more important than such effects, and my 'nonmathy' way to go about this, which has served me extremely well with the mamiya 6: simply scale focus and this will ensure that you stop down enough... but not too much. When in doubt, take two shots. When in serious doubt, take three shots. Eat, drink and be merry.
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  6. #6
    TheFlyingCamera's Avatar
    Join Date
    May 2005
    Location
    Washington DC
    Shooter
    Large Format
    Posts
    8,222
    Blog Entries
    51
    Images
    435
    Also, bear in mind that the lenses for the Xpan are not 35mm lenses, but rather medium format lenses. The Xpan just happens to use 35mm film, but the lenses have an image circle large enough to cover at least a 645 neg.



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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