Paris, Leonard wrote:

> This is just an observation.  If a lens I own says 18mm on it and it's
> really 18.75mm, it's no big deal to me, and I'm not going to start building
> a database of the "exact" tested focal lengths.


I am not sure anyone tests many of them these days, anyway. Relying on 
my memory, increasingly age-damaged, I believe Modern Photography used 
to do that for lenses they reviewed, and as I recall none were exact. I 
believe I read in one of the reviews that the "industry standard" was to 
be within 5% of the rated focal length. So a claimed 20mm lens could be 
anywhere between 19 and 21. No big deal.

Bob
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