Hi Richard,
Okay! there is one possibility - you have got the latest version Zuiko
180/2.8 that has the problem corrected.
I was not the first one to post the chromatic aberration of Zuiko 180/2.8.
Before I brought my 180, I have already heard at least two mailing list
member said that there were problem with their 180. If my memory serve one
have mentioned that his 200/4 did not have this problem.
Now David also posted this problem, but looking back to David's photos I
found the problem seems a bit too much. I just search some of my slides,
found two of my shots that I can identify the problem. I have check them
with a Peak 10x 4 elements achromatic loupe (No. 1983), a Leica projector
with Leica colorplan P2. Follow is the scan with my poor quality Nikon
LS2000. Both shots are hand held, it may not reflect the true quality of the
lenses.
They are posted at:
http://www.glink.net.hk/~olympus/180TEST.htm
Cropped areas were scan with 2700dpi.
Please note that we also have other lenses, problem will not only happen on
the 180 if it was the problem of our slide projector, loupe or scanner. I
have a slide shooting with 85-250, which also has some bright water
reflections, it does not have the same problem like the 180.
At last I want to amend two things:
1. I Just check with some other shots taken with my 180/2.8+1.4xA, where my
wife wore white clothes under bright sun light, they were the tests shot
used for checking of my new 1.4xA. There is no obvious color fringes. Where
there is no over exposure of the clothes, so I expected the problem only
appeared on over exposed white area.
2. I have not formally test the 180/2.8 at different apertures, since I
found the problem with my shot at F5.6 so I expected it was not due to wide
open. And then I made the assumption that "Stop down the lens does not seems
to improve the situation."
C.H.Ling
-----Original Message-----
From: Richard Schaetzl <Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx>
To: olympus@xxxxxxxxxxxxxxx <olympus@xxxxxxxxxxxxxxx>
Date: Sunday, September 03, 2000 1:02 AM
Subject: Re: [OM] Zuiko 180 TEST !!!
>Holla David,
>
> ................
>I couldn't see coloured fringes in the images with the 90mm lens at
>aprox. 30x enlargement. At aprox. 45x enlargement with the 60mm
>lens... oh s##t, some coloured fringes are visible when looking very
>close at the screen! Hmm, crosschecking with an b/w slide. Again
>coloured fringes, on a b/w slide! So it must be the projecting lens.
>End of test, the limiting factor seems not to be the 180mm lens.
>
>So if someone asks why do you use that crapy US$350 lens (new price in
>1992), I'll answer: Because it's an excellent projecting lens used
>within the specs it was designed for, there is no superior
>alternative.
>
>Under that viewing condition, I was able to see chromatic aberration,
>I would have other problems than coloured fringes, seeing the whole
>picture would have been impossible at that distance.
>
>I had an 50mm projecting lens because I like the big picture. I sold
>it because regardless how hard I tried I was not able to have an sharp
>projection, corner to corner. Limiting factor was not the lens but the
>slide not lying flat in the projector. I tried hard, tested all
>available slide mounts, no avail.
>Only solution was looking at the picture from a bigger distance or
>using a lower enlargement, longer focal length.
>My conclusion is 60mm is the shortest focal length one can use for
>standard projection conditions. Those shorter lenses are made for rear
>projection and moderate enlargement.
>
>C.H.Ling wrote:
>
>"Stop down the the lens does not seems to improve the situation."
>
>Conventional wisdom would indicates that the colour error of lenses is
>less noticeable with smaller apertures (only to grow again if an
>optimum aperture has passed).
>
>Did you check that nowhere else in the chain of reproduction has been
>made an error?
>
>I don't care about the performance of my lenses as long as they are
>not the limiting factor.
>
>Anyway it's not possible to cheat the laws of nature. Newton stated,
>it's not possible to eliminate the wavelength (colour) depending
>focusing error. One can only try to reduce it to an usable amount. If
>one tries hard enough, one might reveil the chromatic error of every
>lens.
>
>
>Best regards
>
>Richard
>
>
>*an cheap 10x loupe and an 50mm Zuiko.
>
>**No that aren't el cheapo plastic lenses, both are PC (perspective
>corrections, shift) lenses with full metal lens barrel and multicoated
>lens elements. Those lenses are AFAIK not made by Kodak but either by
>Schneider or more probably by Docter Optic, both have identically
>looking lenses with identical specifications for offer (save the
>writing on the lens barrel). Docter Optic is now owned by Leica and
>"surprise" two similar looking lenses are now available for Leica
>projectors under the name PC Elmarit-P 60mm/2.8 and 90mm/2.8.
>
>
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