Hi, On 12 Nov 2002 at 21:41, Bojidar Dimitrov wrote: > This is just a hypothesis, but I would guess that non-IF, non-FREE > lenses have elements fixed with relation to each-other, so there is no > air movin between the glass surfaces. IF and FREE lenses do have > elements moving WRT others, so there is also air-flow, and thus an > influx of dust.
This is true for primes. And even those have that annoying small metal parts called aperture blades moving between the lenses... Gabor
