Archived posting to the Leica Users Group, 2001/10/07

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Subject: [Leica] Some depth: New LTM Hexanon 35mm f/2 UC-Hexanon in LTM
From: "dante@umich.edu" <dante@umich.edu>
Date: Sun, 07 Oct 2001 23:08:37 -0400

Since Tom A is the only other person I know of who has an LTM 35/2 Hexanon,
and he probably doesn't want to be bothered with giving gory details
(actually, it doesn't matter because that lens is no longer produced), I
will endeavor to write a little about the new 35/2 LTM Hexanon.


Background
- ----------
The 35/2 UC-Hexanon is Konica's third 35mm f/2 rangefinder computation in
seven years.  The first was the Hexar AF lens (which was released in LTM as
the 35/2L Hexar lens); the second was the 35/2 M-Hexanon, which is a more
modern retrofocus design.  The first and final versions are listed as 7
elements in 6 groups which are believed to be close copies of the last
non-ASPH Summicron.  This, I believe is because the original Summicron has a
cemented group that is airspaced in the Hexanon.  The block diagrams I have
seen make this lens a close match of the 35/1.8 Nikkor:

http://www-personal.umich.edu/~dante/352/352.html

Lens Construction
- -----------------
The UC-Hexanon is not like the M-Hexanons (or current Leica lenses), in
several different ways.

- -- First, the UC is lacquered brass, rather than enameled alloy.  You can
see this by looking at the aperture numbers, which shows signs of having
been stamped from a malleable metal rather being than die-cast into a
nonductile alloy.

- -- Second, the "feet" scale is filled in a yellow-orange color (like Leica),
rather than the orange used with the M-Hexanons.

- -- Third, the aperture control is oval, just like Leica, rather than the
round ones used on M-Hexanons.

- -- Fourth, there are incidentals, such as the lens cap reading "Hexanon" and
not "Konica," a real leather lens case, and a vented lacquered hood (which
is safely in the box.

- -- Finally, there is no red dot.  This makes mounting the lens interesting.

Visual comparison to a  Summicron
- ----------------------------------

Sorry about the lousy digital picture (makes everything look bad) - here is
a comparison (color balance is off, but you get the idea).

http://www-personal.umich.edu/~dante/memorex.jpg

- -- In terms of size, the lens is almost exactly the same as the 35/2
Summicron, even down to the dimensions of the Leica-style focus tab (which
you really need when the lens is this small).  The barrel diameter is
smaller, and the "ears" on the aperture ring are smaller on the Konica.

- -- The only difference is that the lens stops at 0.9m in the close range,
instead of 0.7m, as on the Leica

- -- It has a 43mm filter size, and takes a lot more effort to turn the
aperture control (feels a lot like a Canon 35/2 aperture ring, except that
it has half-stops).

- -- Damping is slightly heavier than the Summicron

- -- Coatings look identical, except that the front element on the Konica
reflects green a la Nikon Integrated Coatings

- -- The rear element is significantly flatter and does not protrude as much
into the camera.  No shroud is needed to protect the rear element, as it
sits inside the focusing cam, even with the lens at infinity


And now... to the pictures.

The first thing that is striking about the UC-Hexanon is the bokeh magic
(this much you can see online):

http://www-personal.umich.edu/~dante/bokeh.jpg
(it is from a small print, so it is soft)

The blur of out of focus objects goes well beyond the pale of the original
Hexar lens and even past what I have been able to do with the Summicron.
The new lens manages to achieve very clean disk-bokeh (not the specular
highlights).

When I shot both the UC-Hexanon (on a Leitz adapter) and M-Summicron
(1979-1997 version) at f/5.6, I was stunned to see that there was no readily
identifiable difference in equalized color prints.  On close inspection,
there were two differences:

- -- a tiny bit more snap in the Hexanon (and we are not talking a very tiny
amount) in the shadow separation

- -- less flare from specular highlights (sun reflection in car windshields)
in the Hexanon  

I then checked the negatives with a 15x loupe and could not identify any
difference whatsoever in sharpness at center and edge.  This is not much of
a surprise because comparison to the Summicron at the Photodo site shows
identical MTF graphs for both lenses (at f/2, and identical when the
Summicron is at f/8 and the Hexanon at f/5.6).  Human eyes probably aren't
good enough to see any really subtle resolution differences.

Upshot
- ------
    I think that if someone wanted a screw mount version of the 35/2
Summicron pre-ASPH, this is it.  The lens has some promise, since it can be
mounted on Leicas, Hexars, Canons (finally, a pleasant-bokeh lens that fits
a P...) and Bessas (this actually makes a nice package).

    These will no doubt be hard to get (given the low quantity), but even
listing at $1,000, they are cheaper than the screwmount-ASPH, which is
chrome only, a lot bigger, and to some, less desirable from a bokeh
standpoint.







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