Just when we think that C.H. Ling has found what might be the last
undocumented Zuiko variation (the >500,000 serial number 35-105mm
f/3.5~4.5), along comes another: a rare earth glass (radioactive) 55mm
f/1.2 G.Zuiko. Thanks to Mark Marr-Lyons and Morgan Sparks, who lent
samples, it turns out that there are actually two different optical
configurations of this lens, as follows:
1a. 55mm f/1.2 G.Zuiko M System
1b. 55mm f/1.2 G.Zuiko OM System
[I'm assuming the M System lens is the same lens as the OM System -
as if anyone has actually seen one of these] Both have chromed filter
rings and intense yellow coloration to the glass. The yellow is due to
both the predominant yellow coating color (with minor purple) and the
yellowing of the rare earth glass due to the effects of radioactive
decay. Contrast is superior to variety 2 below, although resolution is
often less. 10.9 oz.
2. 55mm f/1.2 G.Zuiko OM System
This version has a mix of both purple and yellow reflection, due
entirely to the coating. It is an optical reformulation devoid of rare
earth glass (or at least radioactive forms of it). 10.8 oz.
Externally I am unable to find any other noticable differences, besides
the weight.
Copied below are the lens test differences between the lenses. The first
test was the one that has been posted for some time and most likely
represents a silver rimmed, rare earth version.
At the same time I did this comparison, I also did a Minolta MC 58mm
f/1.2 comparison between a radioactive and non radioactive version of
the same lens. Contrast is also enhanced in that radioactive design,
also. The film used for these shots came out purple color cast vs.
neutral for shots from non-radioactive lenses. BUT, they were different
emulsion batches and different periods since expiration.
I need folks with the silver rimmed version and serial numbers between
127,000 and 136,000 to tell me if the color of white paper viewed
through the lens is yellow or white. Just take any other Zuiko to
determine what "white" is.
Gary Reese
Las Vegas, NV
********************
55mm f/1.2 Zuiko (single-coated, rare earth radioactive version with
silver filter rim)
OM-1 with mirror lockup
Vignetting = NA
Distortion = slight barrel
Aperture Center Corner
f/1.2 C+ B-
f/2 B B-
f/2.8 B- B
f/4 B+ B+
f/5.6 B+ A-
f/8 A- A
f/11 A- A-
f/16 A- A-
Notes: Moderate contrast with high resolution, except very low contrast
at f/1.2.
OM-4T with mirror and aperture prefire, different lens than above
Vignetting = C- @ f/1.2, C+ @ f/2, A- @ f/2.8, A thereafter
Distortion = slight barrel
Aperture Center Corner
f/1.2 C- C+
f/2 B- B-
f/2.8 B B
f/4 B B+
f/5.6 B+ B+
f/8 A- A-
f/11 A- B+
f/16 B+ B+
Notes: Moderate contrast images at f/1.2; moderately high contrast at
f/2; high contrast images at f/2.8 to f/4; very high contrast images at
f/5.6 through f/16. Paired comparison to the non-radioactive, black
snout version below, with all grade differences significant to the 1/3rd
grade level.
Comments: This lens utilized one or more radioactive rare earth elements
(lanthium or thorium floride), which are extra low dispersion elements
but with the undesirable side effect of yellowing with age. The
yellowing is attributable to the effects of radioactive decay. This
design has particularily strong radioactivity, which registers on a
Gieger counter through the mirror and the shutter when metered at the
film plane (gamma radiation?). It can potentially fog fast film,
although this hasn't been tested to date.
55mm f/1.2 Zuiko (single-coated, non-radioactive version with all black
filter rim)
OM-4T with mirror and aperture prefire
Vignetting = C- @ f/1.2, B- @ f/2, A- @ f/2.8, A thereafter
Distortion = slight barrel
Aperture Center Corner
f/1.2 C- C+
f/2 B C+
f/2.8 B+ B
f/4 B B
f/5.6 B+ B
f/8 B+ B+
f/11 B+ B+
f/16 B+ B
Notes: Moderately low contrast images at f/1.2; moderate contrast images
at f/16; moderately high contrast at f/2 to f/4 and f/11; high contrast
images at f/5.6 to f/8. No color cast, nor discoloring with age. Paired
comparison to the radioactive, silver snout version above, with all
grade differences significant to the 1/3rd grade level.
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|