[Leica] Of F's, O's, T's and little numbers

[Alex Brattell <alex@zetetic.co.uk>]

Thanks for feedback on my little  'f for what?' mystery.

Bought myself a brand new silver 50mm Summicron. What a treat, and a very
indulgent way to carry less filters around (ok, I'll admit it, I just
fancied a brand new silver lens!). I'll report on 50mm 'lux vs 'cron when
I've put a good few rolls of film past it. 

I was puzzled by the small number '22' beneath where it says 'feet' and next
to the 'm' for metres, but turned 90 degrees. There is also a number on my
50mm Summilux, but that says '16'.

I rang my dealer, Andy Reilly, about it, he didn't know but thought the f in
f-stop stood for 'fractional. He also said that a while back a customer had
pointed out a zero in front of the serial number that appeared on the box,
but not on the lens. This apparently was one of Leica's little codes that
signifies a change in the coating of the lens, bombarded with extra
neutrinos or some such, to make it tougher.

He recommended I 'phone Francois Prinz, technical advisor Leica UK. Mr Prinz
was extremely friendly (he has taken over from the equally friendly Mr
Ridgely, father of former 'Wham' singer, who has retired). He said that the
f thing could be focal or fractional. Think I'll settle on focal number, as
was suggested here. He added that T-stops, as used for cine cameras and not
far off equivalent to f-stops,  stood for Transmission, much more logical.
As regards the little number on the lens, Mr Prinz said it was a Leica code
that indicated the exact focal length. But why make it a code and why put it
on the barrel, does it make any difference at all to the user?

Alas the lens might have to go back because it will go perfectly to infinity
on the body that I had with me in the shop, but is a tiny bit off on another
body, maybe just enough to be irritating. My Summilux 50mm and other lenses
are perfect on both bodies, so I'm not blaming the cameras. Does anyone have
any thoughts on why this might be?




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                         alex@zetetic.co.uk
    http://www.users.globalnet.co.uk/~abrattell/

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