[GravastarNew Member Join Date: Jul 2013 Posts: 2 Offline]

See the thread here. Very annoying and frustrating! Best to read though all the posts from the beginning to extract snippets of useful information.

Bob.

[GravastarNew Member Join Date: Jul 2013 Posts: 2 Offline]

[GravastarNew Member Join Date: Jul 2013 Posts: 2 Offline]

Iceman is correct. For example the Leica Data Sheet for the Vario-Elmar S 30-90mm gives the position of the entrance pupil (from apex of 1st lens element) for two zoom positions as WA: 72.8 mm / Tele: 65.9 mm. If the way this is quoted is similar to that of the M series lenses then the entrance pupil is measured back from the apex of the front element ie. it is behind the front element.

Bob.

[GravastarNew Member Join Date: Jul 2013 Posts: 2 Offline]