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e-mount crop lens fitted to a A7?

Discussion in 'Sony Alpha E-Mount Lenses' started by adwb, Jun 7, 2016.

  1. adwb

    adwb TalkEmount Regular

    127
    Sep 30, 2015
    Bristol UK
    Alistair
    ok so I know that if you fit a full frame lens for example a 50mm f2.8 to a 1.5 drop factor body the effective viewing size become equivalent to a 75mm and the f stop becomes an effective f4 as far as dof goes, but what happens if you fit a e-mount crop frame lens to a A7 , in auto it also looks like a 75 mm but there also the same shift in DOF?
     
  2. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    Yes, when you use the A7 in crop mode it behaves exactly like an APS-C camera with about 10 MP.
     
  3. adwb

    adwb TalkEmount Regular

    127
    Sep 30, 2015
    Bristol UK
    Alistair
    Hmm thats what I thought. I was going to use a Sigma Art 60 f2.8 which is a very sharp lens but at F4 equivalent DOF it kind of spoils what I had in mind.

    sitting on the fence over a Batis 85 or 90 macro and wondering what Sony and Tamron [who belong to Sony anyway] are going to come out with???
     
  4. cvt01

    cvt01 TalkEmount Regular

    164
    Jan 3, 2015
    Yes.

    DOF depends on aperture and subject distance. If you did not change these two when going to crop from full frame then your DOF stays the same. The crop will change though. To address the crop change you have to move back and that changes your subject distance which increases DOF.