What is 'The OM System Lens Handbook' ? Who is the author ?
My recollection of gathering information on which Zuiko indeed
specify extra low dispersion lens used. They are:
24mm/f 3.5 PC
100mm/f 2.0
180mm/f2.0
250mm/f2.0
350mm/f2.8
35-80mm/f2.8
I remember sending inquiry directly to Olympus Japan public relations
department sometime in 1998. And the above was the answer. I also
have the 1998 edition of Zuiko Lens Group brochure in Japanese and
only the above lens have the description of ED term used.
End of discussion.
Jim Terazawa
Hans van Veluwen wrote:
> : ===================
> : We went through this before. The Zuiko 300/4.5 does not have ED glass.
> : Please see FAQ page at: http://brashear.phys.appstate.edu/lhawkins/
> : at section L2.
> : ===================
> :
> : It may or may not. I've discussed this with folks at Olympus USA tech
> : support and at different times have been told conflicting information
> : about whether the 300/4.5 used any low dispersion elements.
>
> For what it's worth, here is how the glass of the 300/4.5 is described in The
> OM
> System Lens Handbook:
>
> "The front of the lens features a luxurious 4-elements in 3-groups
> construction,
> with a combination of high refractive index glass and extraordinary partial
> dispersion glass to greatly reduce chromatic aberrations."
>
> Extraordinary Partial Dispersion? EPD? Hmm, it almost seems that, to use
> Olympus'
> words, this lens "unfortunately has a very high quality"... ;)
> I doubt, however, that this is the same as Extraordinary (Low) Dispersion
> (ED).
> But still they don't use this term EPD for the 400mm and 600mm Zuikos, so that
> makes the 300/4.5 special.
>
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