Archived posting to the Leica Users Group, 1997/05/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hal Robinson wrote: > > Thanks for helping me with my viso and various lenses a few weeks ago. I > have tried different lens and all seem to work fine. I had excellent > results with my dr summicron set at 18 inches. My only question is how many > stops do you lose when a lens is put on the viso in this way for close > focusing. I have found this to be the case with my 90/2 and 502 after this > role I just got back. I am guessing it is around 1-2 stops but not sure. I > didn't even think about losing stops until after i shot the role, and i use > a hand held meter with my m4. Thanks again, Hal > Hal, Did you get an answer for this? I would need a bit more info to answer your specific setup, but keep in mind that when you focus to 1:1 your loose 2 f stops. So a 90mm f/2 at 1:1 would be f/4 wide open. The formula is T = D squared/F squared Where T is the increase in exposure, D is distance from lens to film plan, and F is the focal length inscribed on the lens. Its really one reason that fully automatic SLRs are good at closeups. Dennis - -- Experience is a tough teacher. It gives the test before the lesson. - -unknown