Archived posting to the Leica Users Group, 1997/12/16
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Alf: Perhap this is just personal voodoo, but it has been my observation that with many wide angle lenses there is an infinity focus softness that is greatly reduced by not focusing there. I have seen this with Nikkor 24mm and 20mm, Canon EF 24mm and the 28mm Rokkor for the CLE. Is short, better infinity focus is achieved shooting at f5.6 or f8 when the lens is not focused at infinity but at about 15ft, with the infinity marker aligned with the f4 mark on the DOF scale. Am I nuts? Tom At 09:52 AM 12/16/97 +0100, you wrote: >Milos: > >Usually all lenses are corrected for a certain distance, which agrees >to the distance which is probably used most for a certain focal length. >So, while the 50 mm is corrected for a distance at something between >2 m and 5 m, the correction for wide angles agrees to a more close >distance. It would be unreasonable to correct a 21 mm for i.e. infinity, >if you need the lens's best properties at - let's say - between 0.9 m >and 2.5 m. So, I think, that both the 28 mms, that I had, suffered at >infinity from the correction to close distances. > >Different, the infinity "lack" of the 1.4/35 asph M Summilux should have >another reason. I remember Erwin Puts mentioning, that the 24 mm (I >believe it was the 24 mm), he was testing some weeks ago, showed the >same "behavior". Erwin suggested, that this might be a general property >of aspheric lenses, but he wanted & needed some more investigations. > >Different to my 2/35 Nikkor, the mentioned Leitz lenses have no floating >elements. > >Alf >----------------- >At 22:40 15.12.1997 +0100, you wrote: >> One possible explanation for unsharpness at infinity >>might be the lens design itself favorizing close distance performance. I >>don't know, but do these lenses have CRC? > > >