----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxx>
> I believe sample variation is unavoidable. In factory new units, I
> believe it was quite small, and probably insignificant for all but the
> occasional outlier. With used lenses, I think the possibility of a below
> average sample is increased, as the effects of handling show up in some
> samples.
>
I have disassembly and clean more than 15 different OM Zuikos, I have
confidence on the OM lens construction. Unless the lens has been dropped,
wear out or dry out without proper grease in between the threads (serious
one may cause left/right resolution unbalance) otherwise sample variation
shall be rare. My favourite wide 24/2 had three different lens elements
replaced (at different time) and still sharper than the 21/2 and 28/2 I
have, this indicate variation between lens elements and error in workmanship
(or the chance you make it wrong) is very low.
This does not apply to the latest DZ lenses, I had a 14-45 which is one side
sharper than the other and a 11-22 which had some play in front element
group due to wear out by zoom action and unable to focus to infinity at 18mm
when it is slight pull out.
> Nevertheless, this thread started with two images of birds taken with
> 200/4 and 2XA. You are the one who raised the 200/4 vs. 180/2.8 issue.
> Neither has the FL needed without a 2x. So I naturally looked at the
> performance of both with 2XA. In fact, in Gary's tests, they perform
> comparably both with and without the 2XA.
>>
I agree, according to Gary's result 200+2XA looks promising, this is what I
have never tried before, even yes, without an excellent support I won't use
this combination with OM bodies.
>>
>> My experience was based on the same sensor (E-1/E-3) so APS vs FF does
>> not apply.
>>
> I believe it does, as you are using results with an even smaller sensor
> to compare to results with FF film. If you magnify each the same amount,
> so that the 4/3 image is half the height of the film image, there's no
> problem. If you magnify the 4/3 image twice as much, the the image with
> the same lens may look quite different from the two systems.
>
I'm comparing different lenses on the same 4/3 body, the best one will still
be the best in FF (at least the center, that matter more in this
comparison).
>
> If the test was indeed performed using an OM-1, whereas the test I
> referred to was performed with an OM-4, mirror and aperture prefire and
> the Bogen lens support, that alone would account for the differences.
I doubt they are using sample printed resolution chart and a camera body for
the test, I think pop photo using special equipment. BTW, high speed flash
illumination will eliminate all vibration problem.
> I just don't believe that Modern's test is representative of the
> capability of the lens in general. Whether a result of use with an OM-1
> and no vibration control or simply a bad sample, I can't know. I do know
> your results with 200/4 and E-1 aren't universal.
>
> I can quote AG from February of this year.
> -------------------------------------------------------
> On my E-1. the 200/4 is the cat's meow, but on the OM bodies it is
> excellent, but problematic at times.
> -------------------------------------------------------
> And from Nov. last year:
> -------------------------------------------------------
> Hi all. Any opinions on what OM lenses are the best match to......
Thanks for the example, but it has nothing to do with 180/2.8 and 200/4
comparison or if 200/4's performance is on par with other OM teles.
Different people has different demand on lenses quality, some are easliy
satisified.
>
> So did you and Ian end up with crappy 200/4s, Chuck and Gary with good
> ones and AG with the magic one? I have no idea, but I am pretty sure
> that the 200/4, used correctly, is not on average below the standard of
> the other Zuiko (non-white) teles.
>
My 200/4 is MC, cosmetic 75-80%, perfect glasses with smooth and tight
focusing, my 180/2.8 is 70% cosmetic, very little scratches on front
glasses, I have used light grease to make the focusing easier. Both should
have no problem in optical quality. My 200/4 is not bad but just not as good
as 180/2.8.
Actually, I also made a lots of lens testes in the pass, using Velvia with
flash, Negative and digital but I have no confidence on saying they are well
controlled and accurate since I found focusing is a very hard to control
issue (both human error and camera body focusing accuracy).
It is now totally different, using live view and flash, error is absolutely
minimized. Here is a test I just made, tripod mounted 40D, 430EX bounce off
ceiling, live view, 2 second shutter delay. At least three shots for each
lens with re-focus and selected the best one (actually very little
difference for the same lens). Same development parameters, WB 5200K,
sharpness=2. Both lenses set at F4, the results speak for themself.
http://www.accura.com.hk/200vs180/IMG_3805-180.JPG
http://www.accura.com.hk/200vs180/IMG_3805-180.CR2
http://www.accura.com.hk/200vs180/IMG_3806-200.JPG
http://www.accura.com.hk/200vs180/IMG_3806-200.CR2
C.H.Ling
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