Archived posting to the Leica Users Group, 2005/01/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Adhesives are widely used in almost every engineering discipline now. It is lighter and cheaper and plenty strong and accurate enough. I do not agree that the recent lenses are necessarily better than older because of modern machining though. They certainly no longer need massively skilled technicians to assemble them, but the old stuff, hand assembled, shimmed and carefully inspected during assembly should all be the same as each other within similar tolerances to recently lenses, it just takes more manual skill and time to achieve the same level of consistency. That is not to say the recent designs are not optically better, my 35 f1.4 aspherical is comfortably the best 35mm lens I have ever used, obvious even on the RD1, it is just that my experience of precision mechanics shows me that it is much cheaper and less skilled to reach the same level of precision nowadays than 30 years ago, but the final level of precision is no greater today than then. Materials, OTOH are hugely better today than then. Frank On 26 Jan, 2005, at 05:03, John Collier wrote: > In the old days it was impossible to make precise enough lens mounts. > Every element had to be hand fitted, shimmed and centered. Glue would > be a foolish attachment method as the likelihood of making mistakes > was very high. In short there was a good chance you might have to take > it back apart to get it right. > > Now machining precision is phenomenally accurate. This eliminates the > costly hand fitting. If you compare the lens schematics of the old and > new 50/1.4s (non-Asph) you will see what I mean. Same formulation but > the newer glass has precision mounting surfaces. > > This means that we get smaller sample variation and generally better > overall performance as the manufactured lens is much closer to the > ideal. > > I do not mind that my lenses have to be heated to be disassembled. I > am just so d***ed impressed with their performance I don't care! > > John Collier > (who has on occasion lost in the sample variation game with older > lenses) > > On 25-Jan-05, at 12:20 PM, Didier Ludwig wrote: > >> Slobodan's concern is justified, IMO. As it was presumably me >> starting the thread about glued lenses and heating them, I can only >> repeat what the Leica specialist from Karl Ziegler Fototechnik, a >> reputed camera and lens repair company near Zurich, told me: Most, if >> not all, of the newly designed Leica lenses have more or less glued >> parts or blocks inside. It allows smaller and lighter constructions >> and lowers the engineering and production costs significantly; but >> raises the repair costs on the other side. This is, economically >> seen, good for Leica, but bad for us as soon as we have a lens to >> repair. ALL new japanese lenses were made like that, too, he said, >> manual and AF. It's just the way how lenses are manufactured these >> days, whether in Europe or in Japan. >> >> Thats why I'd say, don't trade in your old pre-ASPH's for the new >> ones, as they might survive them :-) >> Didier > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >