Quote:
Originally Posted by stunsworth
I don't believe that's true. I don't think it's as simple as dividing the difference between f2 and f2.8 by 2. I'll try to find the correct formula when I have time.
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Steve, the folks who have responded are those who gave me my current level of erudition (?) on the matter at
http://www.l-camera-forum.com/leica-...tml#post576056.
As Luigi said above: Putting together the facts that no one (EP excepted?) has measured these apertures exactly and that Mr Lee advised against advertising the aperture as 2.4, it's possible that the lenses are generally faster than 2.5, though again I recognize that 1/2 stop is the minimum that makes a noticeable exposure difference.
As a meaningless but informative check: Luigi, why don't you check the metered exposure difference between marked f/2.8 and marked f/2.5 on the 75? Just curious whether a difference shows at all. And yes, I know, whatever results you get would apply only to your sample of this one design--but still might firm up the "marketing" aspect of the aperture designation.
Steve--For completeness, see this information from another manufacturer's instruction manual illustrating the camera's interpretation of one-third stop increments.
And by the way--you really look funny with that dunce cap. Take it off!
