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Chapter 7 Leica R-Lenses 1
__Introduction
The zoomlens as a species of lens design has had a strange
evolution. The first design seems to be the Vario-Glaukar
1:2.8/25-80 mm for 16 mm cine cameras, created by
Siemens around 1936. Especially in movies, the idea of a
smoothly changing rate of magnification is very valuable as
it can dispense of the stationary camera, moving on a trol-
ley over rails. The first patent for a zoomlens is from 1902
by a USA company. The idea of a zoomlens is now more
than a hundred years old. The first zoomlenses for 35 mm
cameras were regarded as toys and even during the eigh-
ties of the previous century the Leica company declared
that zoomlenses would never surpass the image quality of
fixed focal lengths. It is Mr Kölsch who deserves the credit
for two major breakthroughs in Leica lens design: the
aspherical surface and the high quality zoomlens. The semi-
nal LEICA VARIO-ELMARIT-R 35-70 MM F/2.8 ASPH and
the Vario-Apo-Elmarit-R 70-180 mm F/2.8 are the proof in
the pudding: zoomlenses can be as good as fixed focal
lengths.
Nowadays the situation is reversed: it are the fixed focal
lengths that must prove their superiority against the chal-
lenge of the zoomlens. There is no doubt: the zoomlens
does not lend itself to high apertures (in the world of the
digital camera this statement is not true!) and the maxi-
mum aperture is F/2.8. But with current film technology
the best ISO 200 and ISO 400 slide films (and 400 ISO BW
films) can compensate for the one or two stops difference
between fixed focal lengths and zoomlenses.
The zoomlens has a higher number of lens elements that
can all be used to correct the optical aberrations and the
designer has more tools to optimize his design. We know
that with fixed focal lengths there is one optimum distance
(or magnification) for which the lens can be corrected. In
zoomlens design the same principle holds: there is only one
focal length for which the design can be optimized. The
choice is obvious: one can select the medium position, the
wide angle side or the tele side. For the new LEICA VARIO-
ELMARIT-R 28-90 MM F/2.8-4.5 ASPH, Leica has opted for
an optimization of the 50 to 90 mm range.
The designer of a zoomlens has more tools to correct the
lens, but the mechanical design and engineering are more
demanding. There is clearly a difference between assem-
bling a lens with 6 elements in a stationary mount and a
lens with 11 elements in a moving mount. It is already a
hefty task to manufacture and assemble components with a
precision within 0.01 mm consistently. The additional requi-
rement for a zoomlens is that this same level of accuracy
must be maintained with moving components. Leica does
check the precision of the lens with a testcycle of 50.000
movements of the lens mount.
This new Leica zoomlens has a number of innovative featu-
res that elevates zoomlens design to a new level.
It is the first Leica zoomlens that has a zoom range above a
ratio of 1:3, to be exact it is 1:3.214, very close to the
magic mathematical number pi (3.14…).
The second innovation is a new and very elaborate mecha-
nical design for the movement of the lens groups.
The third innovation is the ergonomics: the LEICA VARIO-
ELMARIT-R 28-90 MM F/2.8-4.5 ASPH has one of the
smoothest lensmounts I have touched, considering the fact
that the lens has been made for manual focusing with a
fully mechanical mechanism. The size of the lens is relative-
ly small and fits in between the smaller Vario-Elmar-R 28-70
mm f/3.5-4.5 and the larger Vario-Elmarit-R 35-70 mm
f/2.8 ASPH. That is quite good, given the additional focal
length of 20 mm. The diameter of the lensmount could be
held down by employing quite thin but very stable alumi-
nium tubes. If you press very hard on the distance ring, you
will increase the friction and this phenomenon has caused
some users to question the mechanical stability of the new
generation of zoomlenses. This is not the case, and one
needs to get used to the idea that modern lenses have a
different feel compared to previous generations.
The fourth area where innovations can be detected is the
cosmetics: the lens has a beautiful shape and very impres-
sive black finish.
We may add that the lens has its share of electronics with
the electronic exposure compensation, useable with R8/9.
No news here, but one should see it as a fifth area.
The ROM (electronic data and signal relay) contact ledge
transfers information from the lens (focal length, aperture
compensation and vignetting data) to the camera for cor-
rect exposure determination and flash settings (zoom
reflector).