Dear Confused (grin),
Otimised is prehaps the wrong word. Economized is better. What happens is diffraction gets worse at smaller apertures. Most other aberations get worse at larger apertures. There is nothing that can be done about diffraction it is a basic law of physics, but the others can be improved by throwing money at them.
Historically lens designers felt the optimum cost/performance range was about 3 stops down from wide open. But lens manufacturing techniques and materials have improved over the years (50 years ago the modern zoom and ultra wide angle lenses were practical impossibilities), and it is now fairly easy and cheap to produce a prime that is optimized at 1 stop down, so many are. There were, even back in the 1950's, a few very expensive fast (f/2.0 or better) lenses that were diffraction limited (sharpest wide open) available.
graywolf http://www.graywolfphoto.com "Idiot Proof" <==> "Expert Proof" -----------------------------------
Boris Liberman wrote:
Hi!
Recent talk about 28/3.5 and 16-45 zoom performance got me confused.
My (probably very much Boris-the-average) belief was that most lenses are optimized at 3 or so stops from their widest aperture. So, for most f/2.8 lenses it would be f/8 or thereabouts.
Is it right thing to assume? Or there is something quite basic that escapes me?
Unconfuse me, will you please? :)
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