Archived posting to the Leica Users Group, 2007/03/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]This is absolutely true. Depth of focus (not depth of field) is very shallow with WA lenses, as it decreases with focal length. I have two cheap Leica R-to-Canon EOS adapters, which differ by a mere few microns in thickness. I achieve perfect focus at infinite with a 90/2R and a 135/2.8R with both of them, but they loose infinite focus when using a 28/2.8R. With a 12mm this should be drastically more critical. I would stay with the Leica original adapter rings. I do not think to remember the correct formula to calculate depth of focus (was it "focal length by aperture divided 1000"?), but somebody on the list will surely do. Best Ed El 08/03/2007, a las 22:16, Phil Swango escribi?: > Hoppy, IMO the back-focus is more critical on the short focal > length lenses > than the long ones. Depth of field is greater, of course, but a > small focus > error may mean you couldn't quite focus at infinity. I don't know > how big a > problem this would be on, say, a 12mm. > > -- > Phil Swango > 307 Aliso Dr SE > Albuquerque, NM 87108 > 505-262-4085 > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >