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on-lens DOF guide question

Discussion in 'Adapted Lenses' started by rhoydotp, Sep 4, 2012.

  1. rhoydotp

    rhoydotp Mu-43 Top Veteran

    609
    Aug 5, 2012
    Toronto, Ont
    rpamparo
    i have a legacy lens that has the DOF guide on the barrel. does it mean that if I'm using it on the m43, I have to look at the guide that is double the current aperture?

    for example, if I set my aperture to f4, which guide should i be following, f4 or f8?

    thanks, and please be nice with your answers! :biggrin:
     
  2. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    If your set aperture is f/8, then use the f/5.6 scales. You use the scales one stop open from the set aperture. Naturally, your maximum aperture has no scales to use.
     
  3. rhoydotp

    rhoydotp Mu-43 Top Veteran

    609
    Aug 5, 2012
    Toronto, Ont
    rpamparo
    even more confused :(

    Thanks Hikari. But I thought it has to be 2-stops not 1-stop difference.

    I went to the DOF calculator to see some numbers for a 50mm mounted on both FF and m43. Looking at f8 on m43 for a subject 5 meters away, the focus will be between "4.04 to 6/56". But on a 35mm, to get the same DOF, it has to be at f4 not f5.6

    Same with f5.6 on m43 for a subject at 10 meters, to get same DOF, it should be 2.8

    So do I have it backwards, or do you have it backwards?

    50mm on m43
    [​IMG]


    50mm on 35mm
    [​IMG]
     
  4. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    Sorry, you are right, two-stop difference. It is basically the square of the crop factor.