Andre Langevin wrote: > As we are talking about the 15mm, and some Takumar and (few) K lenses > (not A) have an aspherical element, the japanese Pentax Lenses Study > Group seems to give a way to distinguish the aspherical lens fron the > non-asp. > > The feet indication on the ASP would be 7, 4, 2, 1.5 > > The feet indication on the non-asp would be 7, 3, 2, 1.5 > > I don't know if this works out also for the Takumar lenses. > > http://www.ucatv.ne.jp/~tweety/SuperWide/K15_35Late/K15_35Late_j.htm > > To me that seems to be a "typo" on the lens barrel as the 4 feet mark > on the ASP lens is at the same place than the 3 feet mark on the > non-ASP, that is in front of the 1 meter mark. Since when 4 feet > make 1 meter?
Interesting to me, Andre. You were sure such a topic will have raised my ears, weren't you? You can also notice different name lettering on lenses. smc (lower case) followed by wider PENTAX is obviously a late type. However, how can we be assured that 3 insted of 4 and/or smc instead of SMC will mean non-aspherical instead of aspherical? There were several cases when Pentax applied step-by step changes during the manufacturing period of a product, with no sure combinations between different features (the LX is a case history in this field). > But there could be a better way to know which lens is ASP: > > http://www.ucatv.ne.jp/~tweety/Report/Comparison15mm/Comparison15mm.htm This lens reflection proof is related to lenses, hence more reliable to me. The problem could be how to repeatedly produce proper reflections, useful for on-field tests. Dario
