[Leica] (Thambar) Mary to Dan

[MGMcGough@aol.com]

 Dan m'boy - the spot is exactly 1/2" (12.5mm) in diameter, silver on one
 side & black* on the other --- but if not used on the Thambar, it has to be
 glued to a clear or UV filter & then used with a large diameter lens of the
 uncorrected spherical aberration type like the 125/2.5 Hektor - it is just
 not effective on most other lenses of smaller diameter & the f: stop has
 to be recomputed proportionally to the effective fl/dia ratio.

 Mary Grace
========================================================
> YIKES! I was simply considering a simple miniscus lens, as an example.  Now
>  my 'Leetle gray cells' are totally discombobulated!
>  I actually am thinkingg of taking my old 1937 Elmar 90/4 and using the UV
>  filter, putting a dot, proportinal to the area covered by the Thambar, and
>  shooting that wide open....see what happens, maybe serendipity!  Anybody
>  familiar with the diameter or both the front element of the Thambar, and 
the
>  spot on the filter?
>  Dan ( having more fun than I really should have!)
>