Archived posting to the Leica Users Group, 2020/02/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I think there is more to it. Tri-Elmar 28-50 is basically a zoom lens with two groups: a positive focusing lens group closer to the film, and a negative group up front. The distance between them is what determines the effective focal length of the lens. To have a negative group up front and having a positive group in the back is the definition of a retrofocus design. At 28mm, the centre of the lens is well ahead of the focal plane, certainly further than 28mm. This indicates that it is effectively a retro focus lens. At 50mm, it is less so. On Wed, 19 Feb 2020 at 11:21, Frank Filippone via LUG <lug at leica-users.org> wrote: > It is not considered a retrofocus design. > > That's it folks.... Final answer > > Frank Filippone > BMWRed735i at gmail.com > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > -- Ken Iisaka first name at last name dot org or com