[Leica] 50mm Noctilux-M f/1

[delia <louzan@worldnet.att.net>]

Hi Rai ,

Due to multiple requests for copies, I decided to post the article in its
entirety as a tribute
to Bob Schwalberg and Walter Mandler.

Regards to all,

Robert
PS:  If it's too long, send the nasty e-mails to Rai (just kidding)

FIRST LOOK  50mm NOCTILUX-M  f/1
SHARPEST SUPERSPEED LENS YET ?    
BY BOB SCHWALBERG

When f/1.5 was still controversial, it was often argued that faster films
would one day end
the need for depth-defying apertures.  Others held that improvements in
high-aperture
lens quality would encourage greater use of slower, finer-grained, sharper
films.
Everybody was, of course, wrong.  Our era of inflationary film speeds(in
which only
ultraconservatives shoot Tri-X  at ASA 400) had defeated both arguments.
Faster films
appear to demand faster lenses, not the other way around.  The
photographer's goal is
seldom to make long exposures at small apertures, or to take a thin-emulsion
film into
available light for a half second at full aperture.  The idea is brief blast
of big apertures. 
Depth of field remains a problem whose solution lies only in accurate focus.
A case in point is the new Leitz 50mm Noctilux f/1 for rangefinder-focusing
Leica M
cameras, produced by Ernst Leitz Canada, that company's North American
subsidiary
whose "Midland" address has long been a feature of the optical landscape.
Like its 1966
predecessor, the Wetzlar-made Noctilux f/1.2, this piece of 50mm glass has been
optimized for high-aperture, high-contrast performance.
Four days and more than a dozen rolls of practical testing prove that f1 is
now a
realistically workable aperture.  As a matter of fact, the confidence gained
from
preliminary testing enabled me to shoot hurdle-jumping at the 1975 National
Horse Show
in New York's Madison Square Garden at f/1 and 1/1000 sec.
The more obvious characteristic of this new speedster is its extraordinarily
high optical
contrast, with almost no flare wide open at f/1.  In this respect it even
outimages its own
high-speed compatriots, the Noctilux f/1.2, and the Summilux f/1.4.  Closing
down to
f/2-two full f-stops !-narrows the advantage somewhat, but still shows some
gains for the
new Noctilux, particularly when bright-light sources are imaged against a black
background.
Unlike the original f/1.2 version, which employed two aspherical surfaces to
achieve its
sorcery with a relatively simple six-glass, four-group design, the new f/1
uses only
conventional spherical curvatures.  As a result, the simpler design of the
old f/1.2 has
given way to a more complex construction of seven elements in six groups,
with a thin
"air-lens" giving additional correction between its second and third
elements. (See lens
cross-section.)
Walter Mandler, who designed the new Noctilux f/1, told us that this greater
complexity
was needed to win back the correctional freedoms he lost by dispensing with
the two
costly aspherical surfaces.  More lens elements gave him a greater number of
different
curvatures, and more refractive variables.
Even so, this new spherical design was only made possible by the use of the same
Leitz-developed and still proprietory high-refractive optical glasses which
were used in
the aspherical 1966 edition.  According to Mandler, this glass, which has a
refractive
index higher than 1.9, was "indispensable to maintain optimum contrast
through the
entire image area."
These high-index glasses, which make possible more gentle curvatures, act
additionally to
eliminate the need for multicoating.  This is because the refractive index
of magnesium
fluoride (about 1.38) approaches the ideal values wanted for reflection
suppression on
glasses of very high indices.  As a result, the new 50mm Noctilux f/1 is
stated to give an
axial transmission of at least 92 percent.  This is a very high value that
actually exceeds
that of some multicoated optics using conventional medium-index glasses.
If the high-aperture quality of the new Noctilux is unquestionable, its
performance down
the diaphragm scale is.  How well it can compete with the Leica's 50mm
Summicron and
Summilux at stops smaller than f/2.8 is sure to become a squabbling point
for Leica
photographers, and the initial testing we were able to complete isn't
conclusive.  One
thing is certain, however: the new Noctilux stops down a lot more
satisfactorily than the
original version.
Shooting the new Noctilux is not an undiluted pleasure.  It's a heavyweight
at 21oz., with
a girth of 69mm that needs bigger hands than mine for fast focusing.
Fortunately the
length forward of the Leica's bayonet mount is only 63mm, and with its
angled open
lenshood its intrusion into the lower right-hand corner of the M-Leica
finder frame isn't
too disturbing.
The mount is jet-black anodized aluminum alloy, with a parallel focusing
action. 
Focusing ranges down to 3.3 ft. (1 m), and good, firm half-stop clicks are
provided from
f/1 down to f/16.  The hood, which is made of a matte-black plastic, snaps
onto two
orientation pins, a bit of technology borrowed from the Leicaflex lenses.
All mathematics to the contrary notwithstanding, the f/1 depth of field at
close-in
shooting distances-less than two in. at five ft.-is surprisingly generous at
longer shooting
distances, as witness my wide-open horse-show pictures.  In many cases I was
banking on
out-of-focus backgrounds that simply held together.  One may argue that this
would be
neither a problem nor a question aboard an SLR, but with f/1 there is simply
no substitute
for the vastly increased accuracy of rangefinder focusing, and the tighter
lens-to-film
tolerances inherent in the simpler rangefinder camera body.  Without
rekindling the old
rangefinder-versus-reflex war, the new Noctilux f/1 and its on-film gains in
high-aperture
image quality make some powerful points for the Leica.
E. Leitz Inc. has announced that the 50mm Noctilux f/1 would be available in
January,
with a suggested retail list price of $855.  This, incidentally, is about a
third less than the
price of the old f/1.2 version, and a splendid argument for spherical,
rather than aspherical
surfaces.

CAPTIONS:

Complex cross-section of new Noctilux f/1 shows modified Gauss design, with
a thin "air
lens" between its second and third elements.  Highly refractive Leitz
optical glasses were
necessary to achieve high image contrast without aspheric surfaces. Quality
exceeds that
of old f/1.2 Noctilux, particularly at small openings, and stops down to
f/2.8 are actually
better than those of other 50mm Leica lenses.

The Noctilux focuses down to 39in. with rangefinders of Leica M2, M3, M4,
and M5. 
Lens can be used with Leica CL, but shorter rangefinder base and blocked
viewfinder
don't recommend it for this model.

The combination of f/1 at 1/1000 sec proved almost ideal for freezing
hurdling horses and
riders.  Depth of field at f/1 isn't much, but a lot more than one might
expect.  At five ft.,
the 50mm Noctilux gives about two in. of effective depth, almost equally
divided before
and behind the focused distance.  When the distance is greater the depth expands
surprisingly, and at 50 ft. it's roughly 17 ft. wide, about seven ft. ahead
and 10 ft behind.

We used only one exposure for the National Horse Show, f/1 and 1/1000 sec,
on Tri-X
rated at ASA 400.  Even the brilliant carbon arc gave a flare-free Noctilux
image.

MODERN PHOTOGRAPHY 
February 1976, p.81