Archived posting to the Leica Users Group, 2001/01/08

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Subject: RE: [Leica] Leica R 24mm f2.8 & 180mm f4 questions
From: Jem Kime <jem.kime@cwcom.net>
Date: Mon, 8 Jan 2001 20:47:40 -0000

Martin,

It's not just Leica that would wish to claim superior light transmission 
for their lenses, so the reality is that maybe Leitz might have a fifth of 
a stop over some lenses and maybe 2/3rds of a stop over the worse (and 
maybe lose out to some of the better other lenses, especially if its an old 
and dirty Leitz lens), this is guessing, not taken from measurements.
But the latitude of film and processing means that if we need to be 
critical we fine tune our working processes. If we aren't critical we say, 
'Ah shucks', that's another one down to experience and put the slight 
difference be down to our technique ...

Jem

- -----Original Message-----
From:	Martin Howard [SMTP:howard.390@osu.edu]

Jem Kime jotted down the following:

> As the film industry noted many years ago, F stops are only theoretical 
values
> of light transmission not the true values actually obtained. For this 
reason
> the professional cine industry works to T stops, (standing for True). I 
was
> often told in my youth by my father that a Leitz lens of F2.8 would equal 
a
> lesser lens of F2, at that time I didn't understand but can appreciate 
what he
> was trying to say now.

Then how come incident light meters work with Leica cameras and do not
result in overexposure?

M.

- --
Martin Howard                     |
Visiting Scholar, CSEL, OSU       |              Shit happens.
email: howard.390@osu.edu         |
www: http://mvhoward.i.am/        +---------------------------------------