Hi Dawid, Iwert, Michael, Wayne, Edward, Chuck, Warren and all,
From: Dawid Loubser <dawidl@xxxxxxxxxxx>
>Now that the Zeiss Distagon 18mm f/3.5 is available for EOS mount, I
>am curious about two things:
>
>* How does the Zeiss compare to the OM Zuiko 18mm f/3.5 ?
>* Do you think there is any chance of the prices of the 18mm dropping
>because of this?
This is an interesting thread... I have owned the older Zeiss 18/4 (in
Contax/Yashica mount) for nearly a decade, and recently got my hands on a
Zuiko 18/3.5 -- I haven't compared them directly so far.
From: iwert bernakiewicz <zuikooh@xxxxxxxxx>
>I've read that the Zeiss is sharper at the center but not to look at
>the corners:).
>(the same is true about the zuiko till f5.6/8)
Can't say about the new Zeiss, but I was very pleased with the performance
of the older Distagon. AFAIK (and according with my still short experience
with it) the Zuiko is a _great_ performer, even wide open.
>The zuiko is the more compact lens...
Sure. Even the older F4 Distagon is more compact than the newer F3.5
From: Michael Wong <mialop@xxxxxxxxxxxx>
>Vignetting is
>observability at wide open, F8 and lower speed will be better.
Again, can't tell about the newer, but my old 18/4 had severe light
fall-off/vignetting wide open... but it was almost gone by f/5.6!
>As Cosina
>Zeiss style, I believe that contrast, color saturation are higher than
>Zuiko's.
The modern trend is to enhance the contrast in the optical design, even at
the expense of some resolution. Comparing the MTFs of the older 18 with the
newer one, this makes sense.
>Compare with
>Zeiss 21/2.8, the quality of edge is poor than 21/2.8 if 100% viewing.
If that 21/2.8 has the same optics of the Contax/Yashica version, then it's
an OUTSTANDING lens!
...but also really BIG! Incidentally, the external dimensions (length,
diameter and weight) are esentially the same of the Tamron SP 500mm F8
catadioptric lens (!)
>Moreover, as Iwert said, the
>size of Zuiko's is much smaller than Zeiss's as 49mm (without adaptor) or
>72mm (with adaptor) vs 82mm filter size.
Yes. The older 18/4 had no filter thread, but can use 86mm filters thru a
specific adaptor.
From: "Wayne Harridge" <wayneharridge@xxxxxxxxxxxxxxx>
>Dunno about the vignetting Michael, all lenses exhibit a falloff in
>illumination proportional to cos**4 of angle from the axis (just a result
of
>the optical physics) so this is a non-negotiable property of the lens.
A word of caution about that... the proper formula for light fall-off is:
cos(w1) * cos(w2) * cos(w3) * cos(w4)
If the lens was a single, perfect, infinitely thin element, then
w1=w2=w3=w4, thus it reduces to the famous cos**4(w) you mention.
But in a real, complex wide-angle lens, each angle has a different value --
all related to w1, the incidence angle from the axis. Particularly, in
retrofocus designs for SLRs, w4 is much lower -- rarely beyond 25-30
degrees, so its cosine is near 1 and thus safely dismissed.
From: "Sawyer, Edward" <Ed.Sawyer@xxxxxxx>
>Hard to say until someone does a comparison. The Zuiko is better than the
older
>Zeiss 18/4, particularly in the corners.
This encourages me to test them ;^)
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
>From Mike Hatam's tests of Zuiko 18/3.5, Contax Zeiss 18/3.5 and Canon
>16-35/2.8 Mark 1
><http://www.16-9.net/lens_tests/18mm_testb.html>
Interesting link, unfortunately the Zuiko is tested @ f/11, whereas the
other lenses are @ f/8, sort of invalidating the results...
Another issue I was suspicious about for years, but never dared to check...
some lenses do perform differently on digital than they do on film -- some
better, some worse. Now I'm quite sure about that :-(
From: Dawid Loubser <dawidl@xxxxxxxxxxx>
>The Zeiss can't be much better, that's for sure (from what tests I've
>seen of the Zuiko).
A while ago, being disappointed by the Zuiko 35/2, I studied tons of MTFs
from different brands, in order to decide which (affordable) one to switch
to. Zeiss was the winner, although the figures weren't directly comparable
(different tests) but the Zuiko 18mm seemed the only real threat to the
Zeiss equivalent (and to other brands too)
From: "Sawyer, Edward" <Ed.Sawyer@xxxxxxx>
>It's not that it's sharper in the corners than the center - the center is
sharper. But >the sharpness is very even across the whole frame, so the
corners are effectively >sharper than the competition. The zeiss is probably
sharper in the center I think, >but the even-ness of the Zuiko is one of the
best things about it. Some tests of >various lenses here :
>
>http://www.edsawyer.com/lenstests/
Thanks for the link!
>Keep an eye out. I managed to score 3 at one time, not long ago. I kept one
of >them.
>
>http://enigma.unh.edu/edsawyer/oly18/oly18web1.jpg
Yummy! My 18/3.5 has a stuck 72mm adapter on it, so I can never get that
view... but then it seems good luck ;^)
From: Warren Kato <wkkato@xxxxxxxxx>
>Well, I didn't really like my Z 18/3.5 like I do the 21/3.5 so I sold
>it. But based on those Italian tests I should probably try again.
Funny! IME, the 21/3.5, although being a nice little lens, it's just an OK
performer, not quite up the level of, say, the 24/2.8 -- a real gem on the
OM System. However, my last test on digital showed the 21 as much better
than the 24!
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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