ZEISS HOLOGON
Zeiss Hologon 15mm f/8 on
Leica M4-P
Modern lens design techniques
have presented us with a relatively large number of super wide angle lenses of
15, 13 and even 12mm focal length. All
of them are very complicated, multi element designs in order to avoid visible
distortion and lack of sharpness due to under corrected optical
aberrations. These lenses have become
actually quite common, and few photographers even remember the super wide lens
which started it all.
For many years, 21 and 20mm
lenses were the maximum 35mm photography had to offer. Anything with a wider angle of coverage had
to be of a fish eye design with all the draw backs of pronounced barrel
distortion. All of this was changed with
the introduction of the Zeiss Hologon 15mm f/8 in the early 1970s. This was unusual in many respects. Not only was the Hologon the first lens to
achieve the unheard of angle of coverage of 110° without the usual fish eye
effect, it was also the first post-war marriage between Leica cameras and Zeiss
lenses.
Cross section of the three
lens elements and the lens position inside the Zeizz Hologon camera body
Note the extreme proximity of
the rear lens element to the film plane
The Hologon was initially
developed for the Zeiss Hologon camera, which was part of the Zeiss Contarex
system. At the time it was thought
impractical to offer the Hologon as an interchangeable lens, even with mirror
lock up in the reflex Contarex. Instead,
Zeiss opted for a separate camera body, based on the Contarex with the mirror
box removed and with the lens permanently installed. It was their claim that extremely precise
registration and centering was necessary for the lens to perform
satisfactorily.
The Leica M cameras also met
these criteria and the lens was made available in the Leica M mount also. It was sold with a special 15mm viewfinder
included. The 15mm Hologon with its
undistorted 110° diagonal angle of view is probably one of the most interesting
lens designs ever. Conventional lens
design theories would indicate that a lens with such specifications would have
to be of a multi-element design.
Computer aided research of wide angle lenses for aerial photography was
conducted. The normal concept of using
many thin elements in wide angle lenses was actually revealed as
unnecessary. In fact, only three thick
elements proved necessary to assure good performance of the lens. Subsequently, the Hologon is of a triplet
design, although bizarrely shaped. Thus
we have an example of an optical design which would not have been created by
using conventional methods. Furthermore,
it is safe to say that manual computations for this design would have literally
taken years to complete.
Construction of the lens made
the installation of a diaphragm virtually impossible without compromising
overall performance. It was also
impossible to offer a speed faster than f/8 for the same reasons, even though
some of the modern optical glasses available today might offer the possibility
to increase the speed of the Hologon.
It was felt that the
restriction of a fixed aperture of f/8 would not pose any great
disadvantage. Besides, a graduated
neutral density filter, offering perfectly even illumination across the entire
image area, would effectively render a speed equivalent of f/16. This could also be used in situations where the
standard f/8 aperture would lead to overexposure.
Since the Hologon lens
renders virtually distortion free images, the camera should be used perfectly
level, to avoid excessively converging lines on verticals. For that reason the 15mm viewfinder had a
built-in spirit level, which helped the photographer keep the camera level,
especially when shooting hand held.
The ability of an extremely
wide angle lens to render virtually distortion free images allow the
photographer to shoot many photographs where it is impossible to tell that an
extremely wide angle lens was used. But
this is only one of the advantages of such a lens. The other is that it produces photographs
with a rather different perspective. It
is important to pay special attention to the foreground since the extreme angle
of coverage will show a considerable amount of foreground when the camera is
held level, even when used horizontally.
It is also important to hold a camera with such a lens very
carefully. It is quite easy for the lens
to pick up ones knuckles.
The Hologon was designed to render
optimum performance at f/8 across the entire image area. Due to the optical glasses available at the
time of its design, the lens did not quite show the high contrast level
typically associated with the high quality optics from Zeiss. In practical terms, this will result in
perfectly sharp enlargement up to 8x10 inches.
Bigger enlargements might show a certain lack of crispness when
inspected very closely. Projection of transparencies,
on the other hand, will show no adverse effects, because the projected images
usually are not inspected very close up.
The same is true with big enlargements when viewed from a more “normal”
viewing distance.
The Hologon allowed focusing
from 8 inches to infinity. Considering
the great depth of field rendered by such a short focal length, one might
initially think focusing to be superfluous.
But it was proven that the overall performance of the Hologon could be
improved if the lens was focused properly.
Minneapolis IDS Center
15mm Hologon
15mm field of view
Please note: The 15mm field
of view images in this article are not separately taken photographs, they were
cropped form the original Hologon negatives to present the view of a 50mm lens
Newer, more sophisticated
lens designs have improved the speed of super wide angle lenses and even allow
for reflex viewing. Subsequently, the
Hologon has long been discontinued. But
it deserves credit for having been the first of the super wides, and its
unusual design will always give it a special place in the history of lenses for
35mm cameras. Those who own a Hologon
can consider themselves lucky indeed.
Minneapolis Lumber Exchange
Building
15mm Hologon
50mm field of view
Minneapolis IDS Center
Crystal Court
15mm Hologon
50mm field of view
Minneapolis Lumber Exchange
Building
15mm Hologon
50mm field of view
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
For high quality camera bags and accessories worthy of Leica equipment, go to
http://www.thinktankphoto.com/affiliates-validated.aspx?type=affiliate
CURRENT SPECIAL OFFERS AND DISCOUNTS
I find it incredible that a lens with this wide an angle of coverage could be made virtually without distortion with just three elements.
ReplyDeleteThe people at Zeiss do know what they are doing, obviously.
Delete