On 17/10/03, [EMAIL PROTECTED] disgorged: >> It is between certain groups of elements and the action of focussing can >> suck in / blow out miniscule amounts of dust in the air that must be able >> to move in and out of the lens, otherwise it would not work. Any lens >> acts like a small, slow pump - especially zooms. >> >> Which brings an interesting possibility - creating a vacuum >inside............ > >Or you could do like Leica and others do with their binoculars. With an >IF lens, seal it and fill it with dry Nitrogen so that there is no dust, >no oxidation of greases and no internal condensation. > >Then charge about twice what the opposition does.....
Wow. Fascinating! I never knew that. I suppose with an internal focus lens, if there is compression of air (or nitrogen or whatever), then the design must surely allow it to move to another chamber within the lens? Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=====| www.macads.co.uk/snaps _____________________________ Free UK Mac Ads www.macads.co.uk
