In article <4d1gbe$6ns@earth.njcc.com>, csink@pluto.njcc.com says...

>Many thanks to all those who answered my question. I obviously did not
>realise that there was such "play" in f-stop values. My first reaction
>to this was "how can non-ttl light meters be of any use then" since
>there is variance in f-stop numbers between lenses. I've guessed that
>film latitude makes up the difference. True?

I don't think there actually is much "play" in f-stop values from
lens to lens (if you use a variable-aperture zoom at the short end
of its range where the rating is known, and base the exposure on the
center of the image) - and non-TTL meters work fine, unless you run
into the exception to what I said above. (I do remember well that
first roll of slides shot with a 25mm f4 Zeiss Flectogon for
the Exacta: the slides were DARK. Turns out that that
lens was almost exactly one stop off correct
exposure at every aperture - the lens
was one stop slower than rating. This is
unusual. Mirrors are regularly off by 1/3 to
1/2 stop, and a long Cosina zoom is a bit slower
than rating, but virtually every other lens I have
tried [even otherwise terrible ones] has been reasonably
close to marked speed.) (I'm just having fun with the line lengths:-)
Hope This Helps * * + *+ + * + * *+ + * * + * +
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+ * * + * + * * + * + ** + * + + + * + * + * +
* + + * * + * + + * + * * * + * * + * * + * * * + * *
* * + + *+ * * + * + + * + * + + * + * + *
+ +* * * + + * * + ** * + + * *+ * * + + * +* + +
S N O W ! I T ' S S T I L L S N O W I N G !
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