Jim,
Thanks for the reference. The insruction manual with the Zuiko 300/4.5 lens
does indicates "special glass". Strictly speaking "ED" as Nikon uses the
terms refers to extra low disperion glass (minimal difference in the index
of refraction of over the entire visible spectrum). But there is no
standard for this term "ED", just as with "APO". However dispersion itself
can be quantfied by the Abbe number..... a measure of the refractive index
spread at three Frauenhofer lines in the visible spectrum.
Yet, another strategy in minimizing secondary color aberations in a lens,
perhaps the one used inthe Zuiko 300/4.5, can be to use anomalous
dispersion glass. The spread in dipersion over the visible spectrum is
non-linear. Leica uses this in the M Aspherical Elmarit 24mm f/2.8. The end
effect is the same.....reduced secondary color but the glass used is not
"ED" strictly speaking Olympus doesn't make that claim.
It all comes down to lens manufactures using loosely defined optics terms
so that the At 02:36 PM 12/16/99 -0600, you 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.
>
>Jim Terazawa
>
>Kurt Hurley wrote:
>
>> C.H. Ling,
>>
>> The Zuiko 300/4.5 is an ED design and very sharp, though I haven't put it
>> head to head with Leitz or Nikon 300's. You'll need a body with mirror and
>> aperture prefire for the best results at slower shutter speeds.
>>
>> At 10:12 PM 12/16/99 +0800, you wrote:
>> >
>> >Hi Joseph,
>> >
>> >Have you tried the Zuiko 300/4.5 ? besides the difficult in handling (due
>> to non
>> >IF design), I personal feel this lens is very sharp and excellent in
>> color. You
>> >also forgot to mention the 180/2 which should possess the same high
quality
>> >as the 250/2 and 350/2.8.
>> >
>> >C.H.Ling
>> >
>> >>
>> >>As far as quality, I have owned Pentax screw mount, Canon FD mount,
>> >>Leica R mount, Agfa, and Olympus 35mm SLRs, and have used Nikon's.
>> >>
>> >>Up to 100mm, Olympus lenses can rival and in some cases exceed what
>> >>other vendors can supply. The 50/1.8 Zuiko's I have had and have have
>> >>all been sharper than the 50/2 Summicron-R I had with my Leica R3.
>> >>
>> >>Beyond 100mm, Zuikos have a harder time standing up to direct
side-by-side
>> >>comparisons with Nikon telephotos. Clearly, Olympus is capable of making
>> >>state-of-the-art telephotos, witness the 250/2 and 350/2.8, but most of
>> >>their more normal sorts of teles are older designs that have not been
>> >>updated to run with the pack.
>> >>
>> >>Joseph
>> >
>> >
>> Kurt Hurley IDS 2000 Product Marketing Manager
>> Schlumberger T&T - Diagnostic Systems
>> 1601 Technology Drive San Jose CA 95110
>> email khurley@xxxxxxxxxxxxxxxxxxx
>> PH 408-437-5156 FAX 408-437-9031 PG 408-699-4587
>>
>
>
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>
Kurt Hurley IDS 2000 Product Marketing Manager
Schlumberger T&T - Diagnostic Systems
1601 Technology Drive San Jose CA 95110
email khurley@xxxxxxxxxxxxxxxxxxx
PH 408-437-5156 FAX 408-437-9031 PG 408-699-4587
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