Re: [Leica] Summicron 50 mm question

[Erwin Puts <imxputs@knoware.nl>]

>Well, for starters, they have different lengths and thus MUST be a
>different formula.  Harold Merklinger, a Canadian optical scientist, has
>written on this -- see his web page for details:
>http://fox.nstn.ca/~hmmerk/HMbook15.html
>
>For another, the COLLECTORS CHECKLIST TO LEICA CAMERAS lists a different UK
>patent number for the rigid from the collapsible.  My copy is not at hand,
>nor have I ever compared the two.

Well, I checked the CCLC and the information is as follows: there are four
patent numbers describing the design of several types of Gauss lenses. (one
from 1952 describes a 7 element design, the other is from 1961 describing a
6 element design. Two refer to the n/f version, one covering the mount
mechanism and one the coupling mechanisms. Presumably these two patents do
not refer to a different optical design, just the mechanical side of the
n/f).
Filing a patent does not necessary imply that its design will be produced.
Leitz/Leica have many patents for designs that will never reach the status
of real life production. So citing patents without a firm and proven
connection to a production type can only be interpreted as circomstantial
evidence.
I will not dispute the statements of Mr Merklinger. I give as facts that
the Elmarit-M 2.8/90 and the Elmarot-R 2,8/90 are identical optical designs
while the lenses themselves have different physical dimensions, so also the
2,8/135 for M and R. Therefore the physical dimensions do not tell the
whole story.
On the other hand, if the front lens of one lens has a different curvature
from another one, presumably of the same optical design, then we need to
accomadate this fact. One solution could be that optical designers use a
scientific interpretation of the concept 'optical design' different from
mere mortals like ourselves, who look at lenses without having all the
knowledge.
I am quite puzzled by the fact that no one (to my knowledge) has ever been
able to produce a picture of this different design for the collapsable
Summicron. All books and articles mention the several versions and give
always only one drawing (the standard 7 element version). If it would be so
obvious and easily ascertained why has not one of the reference books a
picture of it and why is there not a single reference of this fact in the
official Leica literature.
Erwin