[Leica] Leica response to Tri Ermar (28/35/50) is retrofocus?

[Ken Iisaka]

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