Archived posting to the Leica Users Group, 2000/03/09

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Subject: RE: [Leica] F stop: how accurate is a 1.4?
From: R.P.A.C.Savenije@AVV.RWS.minvenw.nl
Date: 09 Mar 2000 09:43:50 +0000

Rick Garrelfs wrote

>Hi Richard,

>in fact, I think we agree completely. The only difference is:
>You have interpreted the "1.4" designation as "exactely 1 f-stop less than
>exactely 1".
>In other words: 1.4 is really 1.41421..... etc.

>I have interpreted 1.4 as just that: 1.4, meaning it may well be less than
>exactely 1 f-stop.
>We know the 1.5 only with one digit accuracy too, so when doing the
>calculation I only take 1 decimal significance, and then you also come to
>0,2 f-stop difference
>(instead of 0,199, or 0,169 for that matter).

>But I think perhaps the most useful answer would be: the guy who posted the
>Dilbert scene was probably right :)

You're absolutely right!!

(b.t.w f5.6 = 2^2.5 = 5.65685 which is more close to 5.7 than 5.6!
It does not mean anything at all, but I just noticed it.)

Richard Savenije,
Professor in Belgium beer and Student in Leicalogy (ok B.D. ? ;))