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Errm... I am reluctant to point this out, but a 36" (910mm) focal length lens with a focal ratio of f/4 must by definition have an effective aperture of 9 inches (228mm)
I am guessing that 337mm mentioned in the advert is the diameter of the mechanical housing, not the clear aperture. The caveat to this is if there is an internal field stop for
the purpose of controlling vignetting, in which case the front element may in fact be 337mm, but in any event... it is effectively a 9" lens... period.
But you guys knew that, right?
Last edited by clive milne; 01-02-2012 at 10:40 PM.
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