Hi Joseph:
I agree with everything you succinctly said, except:
> The low dispersion glass in the 300/4.5 is the same thing Nikon
> calls ED glass.
Can you provide a primary source reference on that?
Olympus' "OM System" brochure (1-87) would be another reference, besides my
previously cited "The OM System Lens Handbook (1984). In the former they
state for the 300mm f/4.5 " . . . keeps chromatic aberrations in check with a
combination of high refractive index glass and special dispersion glass." The
"Olympus OM System Zuiko Interchangeable Lens Group" (3-80) manual states:
"incorporation of newly-developed optical glass provides higher resolving
power and a minimum of chromatic aberration." The "Olympus OM System Zuiko
Interchangeable Lens Group" (2-80) brochure states "Incorporating newly
developed optical glass for improved resolution and minimal chromatic
aberration. . ."
It looks to me like engineering puts the reigns on marketing in limiting what
they could claim for this lens. My hunch is that it was just a rare earth
crown glass that wasn't in the lens markers available glass catalog much prior
to 1973. Saying it was "new" is pretty meaningless, as we've all come to
expect when our breakfast cereal gets a redesigned box and a "NEW" moniker.
Gary Reese
Las Vegas, NV
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