Archived posting to the Leica Users Group, 2000/08/09
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]A friend of mine and longstanding Leica user has the following interesting question on sharpness and depth-of-field. A look at the depth-of-field tables for Leica lenses gives some surprising figures. When the lens is turned to the *infinity* position this gives the following: - - 90mm lens: f/2.8: sharp image as from 86.90 meters, at f/4.0: from 60.80m, at f/5.6: from 43.40m. - - 135mm lens: f/2.8: sharp image as from 195.40 meters, at f/4.0: from 136.80 m, at f/5.6: from 97.60 m. - - 180mm lens: f/2.8: sharp image as from 343.14 meters, at f/4.0: from 242.69m, at f/5.6: from 171.67m. - - 280mm lens: f/2.8: sharp image as from 835.00 meters, at f/4.0: from 591.00m, at f/5.6: from 418.00m. These are amazing figures! As atmospheric haze also starts to have an effect as from about 300 meters I would say, how on earth can we get sharp pictures of subjects at some distance? I presume that no manual or automatic focussing aid can differentiate between infinity and 87m for the 90mm, 195m for the 135mm, 343m for the 180mm and 835m (!) for the 280mm. With the M camera (even with the M3) how can one see the difference between 87m and infinity with the 90mm and 195m (!) and infinity with the 135mm? It would be most instructive to have the LUG's opinion, and also Erwin Puts', on this matter. Thank you. Pascal no archive - -------------------------------------------------------- See my photo pages at http://members.xoom.com/cyberplace - ------------------------------------------------------- Leica. Faszination durch Präzision Leica. Fascination and Precision - ------------------------------------------------------- <<< PGP public key available on request >>>