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[OM] T/stops

Subject: [OM] T/stops
From: PCACala@xxxxxxx
Date: Fri, 29 Oct 1999 00:32:02 EDT
Kurt just posted a finding that the 90mm f/2 Zuiko Macro transmits less light 
than a 100mm f/2 Zuiko.  I just thought I'd caution the engineer-types that 
the close-focus aberration correction in certain Zuiko lenses will change the 
effective focal length when close focused.  Internal focusing does the same 
thing. For example, the 50mm f/2 Zuiko is actually 40mm at 1:2 magnification. 
 Thus T/stop calculations ought to include this factor to be precise.

Gary Reese
Las Vegas, NV

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