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Re: [OM] tripod mounting 180/2.8 + Oly 2X?

Subject: Re: [OM] tripod mounting 180/2.8 + Oly 2X?
From: Jim Brokaw <jbrokaw@xxxxxxxxxxx>
Date: Thu, 16 May 2002 20:51:41 -0700
on 5/16/02 4:46 PM, dreammoose at dreammoose@xxxxxxxxx wrote:

> In addition to the f-stop, it hs to do with the angle of the wedges and
> the angle of the light coming in from the lens. I have no idea what's
> being done today, but back in the Nikon F & F2 days, Nikon made split
> image focusing screens for tele (and WA?) lenses in addition to the
> regular ones.
> 
> Moose
> 
> John Hermanson wrote:
> 
>> Half circle (split image) goes dark on all focus screens of that type unless
>> it's made by Canon.  They found a way to make split image screens that don't
>> black out below f4.5 (or whatever the f is).
>> 

Olympus did this too... with microprisms on the 1-6 and 1-7 screens (I
think). It is related to the angle of the wedge or prism sides, a screen
that is usable for slower long teles won't be discriminating enough for fast
short-focal length lenses, so you need to match them up. Then you need a
body for each screen and lens, so you don't have to switch screens all the
time when changing lenses.
-- 

Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney... 


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