depth of field scale on OM lens question.

Discussion in 'Adapted Lenses' started by johnny9fingers, Mar 15, 2010.

  1. johnny9fingers

    johnny9fingers Mu-43 Veteran Charter Member

    When you use OM lenses on an E-P2, is the depth of field scale accurate? I have been considering getting an OM adapter as I have 28mm, 50mm & 85mm lenses and thought it would be fun to give them a go on the E-P2. The only bad thing would be my OM-1n would feel even more neglected.....
  2. johnny9fingers

    johnny9fingers Mu-43 Veteran Charter Member

    :rolleyes: Duh, I found this post by Amin that answers my question. I need to read through the posts here as a lot of the questions I have are already asked and answered :tongue:

    It's very simple. Say you're using the following two cameras:

    OM-1 (35mm frame) with OM 100mm f/2.8 lens mounted
    E-P1 (4/3 frame) with OM 50/1.4 lens mounted via adapter
    Now use those two cameras to take a picture of a given subject at a given distance will have the following effects:

    Framing (angle of view) will be the same
    Depth of field will be the same if the E-P1 lens f-number is set to half the f-number of the OM-1 lens. Ie, the 100mm lens at f/4 on the OM body will have the same DOF as the 50mm lens at f/2 on the E-P body
    Speed (as it relates to exposure) is based on the nominal f-number, and no calculation is needed. Ie, for a given ISO speed, setting the OM lens to f/2.8 and the E-P1 lens to f/2.8 will result in the same exposure for any given shutter speed
    Note that all of the above are true whether you use an OM lens via adapter, regular 4/3 lens via adapter, native lens, or medium format lens via adapter. Any 50mm f/1.4 lens used in any fashion on a body will give you the same framing and DOF as a 100mm f/2.8 lens on a 35mm frame (135 format) body, and the speed of the lens is based only on the actual f-number without any calculation factor.
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