OK Alan, I responded to the Photo.net discussion, as follows
****************
John H. writes:
<< The Zuiko is an early-70s lens of comparable performance with other
180-200mm f2.8 lenses of the that period. >>
The 180mm f/2.8 Zuiko was introduced in January, 1979. It's still in
production and parts are still available.
<< The 10-year-newer designs, the Tamron 180 f2.5, 80-200 f2.8 and Zuiko
180 f2 . . . >>
The Tamron 180mm f/2.5 came out early in 1986. The 180mm f/2 Zuiko in
May, 1985.
One way of looking at the price difference cited by Konrad Beck is that
many Zuikos have appreciated in value, while Tamron's have depreciated.
A 1.4X-A fits a <113,000 serial number and produces favorable results.
I've not seen any references that the updated multicoating in the
>200,000 examples are associated with any optical formula changes which
would preclude using the 1.4X-A with <113,000 examples.
I very recently tested one in the early 101,xxx range and have some high
contrast resolution data at 1:41 magnification using Fujichrome 64T Type
II film:
f/2.8: 73 lp/mm center, 65 lp/mm
f/4: 73, 65
f/5.6: 73, 65
f/8: 65, 51
f/11: 65, 57
f/16: 57, 51
f/22: 51, 45
These data, as well as my tests of a 180mm f/2.8 with and without 1.4X-A
teleconverter ( at
http://members.aol.com/olympusom/lenstests/default.htm ) are in
disagreement with the Modern Photography tests of 7/79 ( transcribed at
http://brashear.phys.appstate.edu/lhawkins/photo/mp-zuiko-tests.txt ).
It is my opinion that the Modern Photography tests suffered from the
same auto diaphragm vibrations that plagued many of my tests using an
OM-1 with mirror lockup. It wasn't until I started testing with the
self-timer activated - thus getting mirror and aperture "prefire" - that
I was able to control this poorly documentated source of vibration. The
180-200mm Zuikos are especially prone to it.
Unfortunately, I never got a sample to test of the Tamron SP 180mm
f/2.5 I'm now out of Fujichrome 64T Type I film, so any further SQF
testing is dependent on some showing up in old stock sales.
Modern Photography reported chromatic aberration in the Tamron 180mm
f/2.5 (tested 6/86), as to be expected from a non-apo design.
Gary Reese
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