Archived posting to the Leica Users Group, 2001/07/17

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Subject: Re: [Leica] Re: should i buy into noctilust
From: "Juan J. Buhler" <jbuhler@pdi.com>
Date: Tue, 17 Jul 2001 15:38:38 -0700 (PDT)

On Tue, 17 Jul 2001, MEBérubé wrote:

> Hmmm. <scratching head and looking at my Elmar 5cm/3.5>
> All I've got here are: 3,5    4,5    6,3    9    12,5   and   18
> 
> Somthin' amiss with my lens or was Oscar mixed up in his math?
> (I'm a History/Humanities guy more than a Science/Math guy, so of course I 
> don't get it.)
> :)

My fake Elmar 50mm has the same markings. Funny, because the dof
markings say 4, 5.6, 8, 11, 16.

It's just that aperture stops were not standarized back when these
lenses were made. The difference from value to value is still one
stop, and the math works in the same way: 3.5 * 2 ~= 6.8, 4.5 * 2 = 9, 
6.3 * 2 ~= 12.5, 9 * 2 = 18. Sunny 16 becomes "sunny between 12.5 and
18"

j

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 Juan J. Buhler | Sr. FX Animator @ PDI | Photos at http://www.jbuhler.com
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