At 01:27 AM 9/27/04, Moose wrote:
>Well, that doesn't agree with my understanding. I've never owned any of
>the f1.2 lenses, so I go on what I've read here and Gary's tests. The
>experiences I recall hearing here are mostly like John Lind's post this
>afternoon where the 50/1.2 is praised. Remember, the 50/1.2 wasn't a
>replacement for the 55/1.2, which had already been discontinued for some
>time, but for the 50/1.4, their flagship normal fl lens, which was
>discontinued when the f1.2 came out..
This is correct . . . it really replaced the multi-coated 50/1.4 although
IIRC there was a time lag between discontinuing it and release of the
50/1.2 during which the only 50mm was the multi-coated 50/1.8 (the late
"Japan" version of which has gotten high praise from its owners).
I don't know of any "ultra speed" lens in the f/1.2 and faster class that
doesn't take an MTF hit when used wide open (there have been some f/1.0's
and Canon even made an f/.95 for its LTM clone long ago). The formulations
for lenses that fast are quite complex with the considerable aberration
correction required for the extremely off-axis ray paths. It's why they
have one, occasionally two more elements compared to an f/1.8 or f/2 design
derived from the same formulation.
With the 50/1.2 and 50/1.4's I've always estimated this to be about one
grade down from f/2.8 or f/4 . . . from the point where even performance
toward their middle apertures begins (e.g. A or A- in the f/2.8 to f/4 will
result in B or B- at f/1.2 or f/1.4). The MTF drops some wide open, but
IMHO it's not much of one even though it's measureable. Some lenses take a
complete nose-dive to a D or F wide open.
Not certain mine would rate as low as a "C" at f/1.2 but I haven't
definitively tested it either and very rarely shoot it wide open. At f/1.2
the DoF is extremely shallow for anything closer than about 15 feet and it
requires very careful focusing at closer working distances. I have never
had any focusing difficulty with it even in extremely low light using 2-13
screens in an OM-4 and OM-2S. Just the opposite; it's one of the easiest
to focus through. Whether or not it is in focus (on the desired subject
matter) is readily evident across the entire focusing screen. If it truly
is a "C" wide open, perhaps the grade at which focusing ease is affected is
lower.
I use the 50/1.2 and the two newest 50/1.4's interchangeably although the
former normally resides on the OM-4 and a pair of the latter are on the
OM-2S and OM-2n. IOW I don't try to keep the f/1.2 on whatever body I'm
currently using. The two newest f/1.4's are plenty good enough in their
own right. Gary's tests on many of the lenses he lists are from one
example and that includes the 50/1.2. There are a few with which he's been
able to test more than one. The results from those vary some. I concluded
from looking at these variations that a specific lens in my hands might
test a grade better or worse at many of its apertures compared to the lens
Gary tested. Manufacturing variations are one factor. Optical condition
of a lens and its history are even more important. Dropping a lens (even
though a filter took all the visible damage) can shift an
element. Reassembly with less than the best possible care for accurate
collimation can also affect performance.
My 1.2 seems just a tad contrastier than the 1.4's at mid-apertures. They
all take a very slight hit in resolution at f/16 (a little diffraction
limiting ??) compared to f/8-f/11 and a slightly greater hit wide
open. Between f/2 and f/11 I don't worry about it at all. Outcome is
affected more by what I'm doing with them than by their inherent
capabilities (e.g. camera shake).
My benchmark and "gold standard" for all other lenses:
Circa 1954, single coated, Carl Zeiss 50mm f/1.5 Sonnar for a post-war
Contax IIa/IIIa. Its f/1.5 7-element 3-group formulation by Ludwig Bertele
dates from the mid-1930's; several thousand pages of hand computations that
stacked about a meter tall. It takes a very slight hit in resolution wide
open. I was stunned by its contrast, resolving power, lack of any visible
cos^4 falloff and flat field the first time I used it and projected the
chromes shot through it on a large screen. With 13 curved-edge aperture
blades, its soft bokeh is very even throughout its aperture range. Their
manufacture required extreme precision; the fast 7/3 formulation would be
much too costly to make today compared to Paul Rudolph's Planar design that
rivals it and Carl Zeiss currently uses it for standard focal lengths. The
multi-coated Sonnar HFT formulation used for 40mm on the Rollei 35S, circa
1980-1982, is an f/2.8 with 5 elements in 4 groups derived from Bertele's
original 7/3. The slower lens speed didn't require as many elements for
aberration correction. Fewer and smaller elements made it much easier to
manufacture. I have yet to use any lens with any focal length on any
camera that meets or surpasses the 50/1.5 Sonnar in any aspect; it is that
good!
-- John Lind
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