You may twist the controls of a 2 touch zoom, but lens groups are still
moving forward and back which will require the movement of air. Perhaps it
isn't so turbulent though. I could never zoom quickly enough with a 2 touch
type.
Mickey
----- Original Message -----
From: "Roger D. Key" <rdk@xxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Friday, June 14, 2002 8:29 AM
Subject: Re: [OM] ( OM ) Dust in lenses
>
> I guess that that is a big plus point for two-touch zooms; no pumping!
>
> Sincerely,
> Roger Key
>
>
>
> Good point. The zooming action has the inside of the lens acting almost
> like a bellows, pumping air in and out.
> _________________________________
> John Hermanson www.zuiko.com
> Camtech, Olympus Sales & Service since 1977
> 21 South Lane, Huntington NY 11743-4714
> 631-424-2121 For Free Olympus manuals,
> please call 1-800-221-3000
> _________________________________
> ----- Original Message -----
> From: "Brian Swale" <bj@xxxxxxxxxxxxxxx>
> To: <jochen.schiffler@xxxxxxxxxxx>; <olympus@xxxxxxxxxxxxxxx>
> Sent: Thursday, June 13, 2002 9:44 PM
> Subject: [OM] ( OM ) Dust in lenses
>
>
> > Hi Jochen,
> >
> > Lenses are not sealed airtight. There's no practical way they can be.
> >
> > Every time a lens is focussed to a different focal length (except for IF
> > lenses), the lens body increases or decreases in length. This means the
> > lens volume alters. Thus air moves in or out of the internal cavity as
> the
> air
> > pressures inside and outside the lens equalise..
> >
> > If the outside air is dusty, dust enters the lens then settles on any
> surface to
> > which it is attracted.
> >
> > And there's your answer.
> >
> > Brian
> >
>
>
>
>
>
>
>
> < This message was delivered via the Olympus Mailing List >
> < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
>
>
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|