> I have heard remarks that a 200/2.8 prime will transmit more light than an
> 80-200/2.8 zoom. Is this true? I thought a 200/2.8 was a 200/2.8 whether it
> be a prime or part of a zoom.
I believe 2.8 should be "effective" aperture, i.e. it should reflect lens construction,
light loss in glass, etc. IOW, 2.8 should be the same be it prime or zoom.
It can't be (as people sometimes say on this list) as simple as
lens diameter divided by focal length; otherwise my FA28-70/4
could not be constant aperture zoom :-)
(But it is possible some manufacturers "cheat" and their lenses
can have significantly different max. aperture than stated)
Ivan
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