Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,672   Posts: 1,481,823   Online: 1125
      
Page 2 of 2 FirstFirst 12
Results 11 to 14 of 14
  1. #11

    Join Date
    May 2003
    Location
    Northern Virginia
    Shooter
    Large Format
    Posts
    421
    I was also a victim of focus shift. For years some were sharp and others not so sharp. Having a high end, big name lens did not eliminate focus shift. I found a top end 80mm Rodagon had shift and a 50 year old 75mm Wollensak showed none. I don't understand how that might work with Ed's answer, but it just is. When I started using a good Peak grain magnifier I had enough range and light to see the focus shift.

    Yes, about two stops down is the sharpest for all my lenses. f/8 and be there.

  2. #12
    Ed Sukach's Avatar
    Join Date
    Nov 2002
    Location
    Ipswich, Massachusetts, USA
    Shooter
    Medium Format
    Posts
    4,520
    Images
    26
    Quote Originally Posted by photobum
    I was also a victim of focus shift...
    ... I don't understand how that might work with Ed's answer, but it just is. When I started using a good Peak grain magnifier I had enough range and light to see the focus shift.
    That is what I was afraid of. Serves me right for trying to condense an entire basic optics class into one message. It is so much easier to visualize, once you have gone through the ... now ancient ... exercise of ray tracing a lens from scratch.

    Every lens is designed from a certain *desired set* of parameters, with "targets" in the center of compromises. Most enlarger lenses will be at their *best* performance in the centers of their aperture ranges, and in the center of their magnification ratios.... But any, worth their salt, will be absolutely *usable* at their published extremes.

    Interesting that you should see *significant* focus curvature/ "shift" errors in Rodagons. I use both Rodenstock Rodagons and Schneider ... (name?) lenses, and I see *nothing* remotely resembling that ... and I've learned a long time ago that it was NOT wise to try to save pennies on grain focusers. Mine is a top-end Omega.

    I might suggest that you contact Rodenstock. The latest Rodagons came with *lifetime* guarantees.
    Carpe erratum!!

    Ed Sukach, FFP.

  3. #13

    Join Date
    Jan 2005
    Location
    Japan
    Shooter
    35mm
    Posts
    1,957
    My Nikkor 63mm lens looks good at F8, which is my standard setting. With the kind of negs I have, I don't really have to change the aperture.

  4. #14
    Christopher Walrath's Avatar
    Join Date
    Dec 2005
    Location
    Milton, DE, USA
    Shooter
    4x5 Format
    Posts
    6,980
    Blog Entries
    29
    Images
    19
    Good info everybody. Thank you very much. I love the Dark Side.
    Thank you.
    CWalrath
    APUG BLIND PRINT EXCHANGE
    DE Darkroom

    "Wubba, wubba, wubba. Bing, bang, bong. Yuck, yuck, yuck and a fiddle-dee-dee." - The Yeti

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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