----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, September 24, 2001 11:35 AM
Subject: Re: lens brightness
> OK folks, I hear what you are saying.
>
> Now, tell me how interchangeable lenses are used along with
those fancy hand held light meters. When you take out your
Pentax Spot Meter, do you adjust it every time you put a
different lens on the camera? Oh, the T-value for that lens is
1/2 stop better than this one?
> (I'm serious here, not pulling your leg!)
I almost never worry about it. I just presume that f/5.6
(example only) is f/5.6 no matter what lens I am using. Of
course, I only use the hand held meter with the large format
camera and a few lenses (non of which are zooms) in the studio.
For macro work with non ttl flash, I calculate the light loss
directly with the built in meter, then adjust the output of the
strobe accordingly.
My exception is with my old (uncoated) 90mm f/6.8 Schneider
Angulon. It definitely needs a half stop more exposure because
of light loss. It's negatives also require 2/3 zone more
development to get the negatives to the same contrast as my
modern lenses.
>
> If I take out my Dad's old 2x3 Speed Graphic and the GE meter
hand held lightmeter, it says shoot at this f stop/speed. It
doesn't say much about T-values for the lens. Is the difference
that marginal that it doesn't matter?
It might be, but it also might not be. In my situation, it
isn't. I think it could well be a problem with zoom lenses with
lots of glass, but these tend to be used with TTL metering, or
with uncoated lenses that have lots of veiling flare (thats
where the light goes when it bounces off the glass rather than
going through it).
William Robb
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