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crop factor

Discussion in 'Adapted Lenses' started by shroo, Feb 5, 2013.

  1. shroo

    shroo New to Mu-43

    Feb 1, 2012
    Hi forum, I wonder if anybody can confirm what the focal length is when I use my OM 50mm 1.8 on my GH1?

    Am I correct in thinking that using an adapted lens would be 50mm x 2?

    Also if it's a native lens, say 45mm 1.8 does that mean it would have a wider focal length that the adapted lens?

    I think I'm over complicating it.
  2. elavon

    elavon Mu-43 All-Pro

    Sep 1, 2012
    Tel Aviv Israel
    All lenses are marked with the focal length.
    The 50mm is longer then the 45mm by 5mm.
    When comparing the lenses to focal length you need to use the 2X crop factor to know the relevant field of view.
    The 45mm on :43: as the same field of view as 90mm on FF (35mm).
  3. blue

    blue Mu-43 Veteran

    Jun 1, 2010
    This is slightly misleading. The focal length of the lens is an actual physical property - nothing to do with the format. A 45mm lens is marked as such because that is what it is.

    Yes, this is correct. The crop factor is about the equivalent field of view.
    • Like Like x 3
  4. WT21

    WT21 Super Moderator Subscribing Member

    Feb 19, 2010
    What blue said.

    The focal length is the focal length. It's 50mm. The angle of view is more narrow on m43 than a full frame (135) sensor
  5. arentol

    arentol Mu-43 Veteran

    Jun 29, 2012
    The only time the listed focal length of a lens is typically different from its actual focal length is on fixed lens compacts where they sometimes only put the 35mm equivalences on the lens, not that actual focal length (which you have to check your manual to find), but even that is fairly uncommon.

    But if the lens is removable then it is 100% irrelevant what camera system it was designed for, its listed focal length will be its actual focal length every single time. A 100mm on medium format is 100m on a 35mm camera and is still 100mm on m4/3rds.

    It is up to you to understand what that means for the system you are using it on. 100mm is kind of long and mostly good for indoor and some outdoor sports on m4/3rds, while it is more for portraits on 35mm, and is a little more narrow than "normal" lens on Medium format.

    And more to your actual question. A 50mm lens designed for 35mm format would be wider than a 60mm designed for m4/3rds and narrower than a 45mm designed for m4/3rds.
    • Like Like x 1
  6. Boneyard

    Boneyard Mu-43 Regular

    Oct 5, 2012
    Iowa, USA
    It depends on whether you are talking photography or videography.

    The GH1 & 2 with their multi-aspect sensors have unique properties. So while taking stills they function like all other :43: cameras and have a 2x crop (in 35mm terms anyway); but in video they actually have a 1.86x crop. Not sure which discipline you were referring to; so if photo the previous posts are correct. If interested in video, take your focal length x 1.86.

    I know most posts on this site lean to the photography side; but thought I would post this in case anyone was interested in the videography side.
    • Like Like x 1
  7. davidzvi

    davidzvi Super Moderator Subscribing Member

    Aug 12, 2012
    Outside Boston MA
    • Like Like x 1
  8. shroo

    shroo New to Mu-43

    Feb 1, 2012
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