Archived posting to the Leica Users Group, 2000/11/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>>>>> > > At 12:56 AM 11/8/00 +0100, Alan Hull wrote: > >So I thought "zone focus" and change to a 35mm lens to increase DOF. > >Which of course is nonsense as DOF has nothing to do with focal length. > > Huh? > Admittedly, I'm not an expert on photo theory and often confuse it all > round, but everything that I was taught, and my brief 20 years experience > hath shewn, that lenses of short focal length produce greater depth of > field than do standard lenses at the same aperture. > > Or did I misunderstand? > > Carpe Luminem, > Michael E. Berube DOF has nothing to do with focal length. DOF is influenced by image magnification and aperture. Shorter lenses have greater DOF for a given aperture and working distance because of the reduced image magnification. Doug Herr <<<<< You're being a bit brutalist here doug! Image mag is a function of focal length and subject distance, so for the same subject distance and aperture, the wider lens has greater DOF. So you're both right! Which just goes to prove that for once, agreement is possible, even on the LUG. So there must be something wrong with my reasoning?.... And rereading it, I realise that you already said this, so shall I post it? Why not! Rob.