Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 77,716   Posts: 1,716,519   Online: 805
Results 1 to 2 of 2
  1. #1

    Join Date
    Feb 2005

    RB67 - Auto Extension Tubes - Depth Of Field


    Another question.

    I have a RB67 and the manual quotes DOF tables for each particualr lens. When using auto extension tubes is there a way of predicting new DOF info from original table?

    The manual does provide magnification range, distance range,and subject size range. It also gives exposure compansation values.
    Last edited by Lyrrad; 07-26-2005 at 11:12 AM. Click to view previous post history.

  2. #2
    Marco Gilardetti's Avatar
    Join Date
    Jun 2005
    Torino, Italy
    Large Format
    Jeez, this is where I'm actually toward learning rather than explaining. However, since nobody answered, my guess is the answer is no, as the formula for calculating DOF in the small distances range has a dependance on the subject to nodal point distance which is not linear, and however can't be approximated as usually it is at great distances. That is, you can't simply move the decimal point about one position, or divide everything by (say) 2, and get numbers which are still meaningful. That said in the macrophotography realm, I repeat, not at "normal" photographical distances. Please someone correct me if I misinterpreted the formula.

    However, you may not want to rely on those charts anyway, expecially in macrophotography. After all, the choosen "circle of confusion" on which these charts are based is never specified (or at least I've never seen one which reported it). I think it's better to rely on what you see on the ground glass, and mostly stop down as much as you can.
    I know a chap who does excellent portraits. The chap is a camera.
    (Tristan Tzara, 1922)



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