Archived posting to the Leica Users Group, 1997/09/16
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Tue, 16 Sep 1997 Leikon35@aol.com wrote: > If by real you mean the actual Transmission (T stop) rather than the > computed (focal length divided by diameter) then those figures sound > reasonable. Even with the best of coatings, there is always a minor > transmission loss. Years ago, marking the actual "T" stop on the lens > was tried but somehow no one really was interested. > Marvin Moss > ++++++++++++++++++++++++++++++++++++++++ > In a message dated 97-09-16 03:29:52 EDT, you write: > << >Subject: real aperture of Noctilux > >I've read on a book about Leicas the real aperture of the Noctilux 50/1 is > >1.17 and the real one of the 50/1.2 is 1.3. > >Can anybody confirm that? > > > >Thanks in advance > > > >Ernesto > > >> > > It probably does not apply in this case but I have been told that the T stop, such as used by Bell and Howell in their famous motor drive 35mm camera of the 50s (60s?), had a basic problem. It is a measure of the actual light being transmitted by the lens, but it also includes the flare light, not just the imageing rays. In the old days lenses produced a lot of flare light. Not the case today. Ed