Question about effective focal length / magnification with reversed lenses

Discussion in 'Adapted Lenses' started by markoneswift, Jul 24, 2013.

  1. markoneswift

    markoneswift TalkEmount Veteran

    Oct 17, 2012
    Hi everyone, I have a question. I have been experimenting with reversing legacy lenses for macro recently and I wondered if anyone could help me out with a calculation. I have a NEX C3 onto which I'm planning to mount a 2x teleconverter and a 50mm F/1.8. I'm then going to reverse a 28mm F/2.8 onto the 50. Does the crop factor have any effect on the reversed 28mm lens, ie am I basically dividing my 160mm ( effective ) focal length by 44.8 or is it effectively still a 28mm if reversed and I divide by 28 ? I'm starting to make my head hurt now ! Thanks !