Olympus-OM
[Top] [All Lists]

Re: [OM] long telephoto advice

Subject: Re: [OM] long telephoto advice
From: "Tom Trottier" <Tom@xxxxxxxxxxxxx>
Date: Wed, 12 Jun 2002 02:13:48 -0400
On Tuesday, June 11, 2002 at 14:19, Winsor Crosby 
<olympus@xxxxxxxxxxxxxxx>
wrote re "Re: [OM] long telephoto advice" saying:

> >In <3D0612F3.15432.3F3583C@localhost>, on 06/11/02 at 03:10 PM,
> >    Tom@xxxxxxxxxxxxx said:
> >
> >>I think that would be better. Mirror lenses lose almost a stop of
> >>light
> >>  from the central 2nd mirror, so that f/8 becomes an f/11, slower
> >>  than
> >>a  300/9.
> >
> >Are you sure that this is true of the Zuiko?
> >
> >---------------------------------------------
> >les clark / edgewater, nj / usa
> >---------------------------------------------
> 
> I think that might be an exaggeration.  To drop the light by 1 stop
> you would have to obstruct half the area of the lens opening. That
> would require a secondary mirror of about 52mm which is much larger
> than the one on the Zuiko which appears to be about 35mm.
> 
> In addition the Zuiko rather stands out from the usual mirror lens
> with an evenly lit field, good correction, and good contrast. --
> Winsor Crosby Long Beach, California

Cross off the "evenly lit" part and you'd be right.

Tom
------- Quidquid latine dictum sit, altum viditur -----------------
   ,__@ Tom A. Trottier +1 613 860-6633 fax:231-6115
 _-\_<, 758 Albert St.,Ottawa ON Canada K1R 7V8 
(*)/'(*)        ICQ:57647974 N45.412 W75.714
---------------------------------------------------------------------
Laws are the spider's webs which, 
if anything small falls into them they ensnare it, 
but large things break through and escape.
        --Solon, statesman (c.638-c558 BCE)


< 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 >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz