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APO
stands for "apochromatically corrected".
In most lenses, optical design concentrates the focus of blue
light and green light into a single plane, but red light falls
slightly into another plane of focus. Red subjects, therefore,
would be ever so slightly out of focus compared to blue and
green subjects in the same frame. Not sure you'd ever notice
though, the difference is so slight. This is the same basic
principle that requires you to shift the focus for infrared
photography, related to the wave length of red light. In APO
lenses, the design and expense has been put in to making red
light focus on the same plane as blue and green. Under a microscope
you would see that all light subject is now in focus, creating
a sharper image overall. Many manufacturers offer APO designs,
but in most of these only the very center of the lens is APO
corrected. Leica prides itself on making most of the frame
APO correcte.
ASPH
… stands for "aspheric design".
Most lenses have a spherical design - that is, the radius
of curvature is constant. These are easy to manufacture by
grinding while "spinning" the glass. This design
however restricts the number of optical corrections that can
be made to the design to render the most realistic image possible.
ASPH lenses, however, involve usually 1 element that does
*not* have a constant radius of curvature. These elements
can be made by 1) expensive manual grinding, 2) molded plastic,
3) Leica's patented "press" process, where the element
is pressed into an aspherical ("non-spherical")
shape. This design allows the manufacturer to introduce corrections
into compact lens designs that weren't possible before. Practically,
the lens performs "better" (up to interpretation)
due to increased correction of the image, in a package not
significantly bigger than the spherical version.
There
is another Aspherical lens manufacture technique: an uneven
coating layer is applied to a spherical lens. The coating
is thicker on the edges (or on the center, depending). Canon
"Lens Work II" calls these "simulated"
aspherical lenses. Simulated and Glass-Molded (GMo) asphericals
show up in non-L Canon lenses, while the L lenses have actual
ground aspheric elements.
Beam
Splitter
Describes the way light travels when it enters the R series
Leica SLR bodies when viewing and composing. The light beam
is split into two - one part goes through the semi-silvered
mirror to the light meter at the base of the mirror box, the
rest is reflected upwards through the pentaprism to the viewfinder.
It is because of this "beam splitting" that you
have to use Circular Polarizing filters on R cameras in order
to obtain correct light meter readings. With regular linear
pol. filters, phase cancellation effects occur when the light
travels through the mirror, resulting in inaccurate and unpredictable
readings.
CLA
An acronym for " (C)lean, (L)ubricate & (A)djust
", whereby the item is merely re-lubricated, fine-adjusted
and calibrated rather than repaired. "I just got
my equipment back from CLA at Leica"
Elmar
Refers to the maximum lens aperture - here f3.5 . Historically
derived from the original 1925 50mm f3.5 Elmax lens, which
was an acronym of (E)rnst (L)ieca and Professor (Max) Berek,
designer of the original lenses. Later that year the 50mm
f3.5 Elmar superceded the Elmax, which was discontinued due
to its complexity and high cost of manufacture.
Elmarit
Refers to the maximum lens aperture - here f2.8 . The name
is obviously derived from the earlier (and slower) "Elmar"
designation. Not every f2.8 lens is called an "Elmarit"
though, the most obvious current exception being the 50mm
f2.8 Elmar-M collapsible lens which for nostalgia and marketing
reasons has kept the original 1930's Elmar name (the 50mm
f3.5 collapsible Elmar, manufactured 1930-59, was one of Leica's
most famous and popular lenses).
Hektor
Refers to the maximum lens aperture - usually f2.5 . The name
was apparently taken from the name of lens designer Professor
Max Berek's dog(!).
Leica
A compound word derived from " (Lei)tz " and "
(ca)mera ". Apparently they were originally going to
use "LECA", but another camera company already used
a similar name in France, so they inserted the 'i' to prevent
any confustion.
M
(as in "M3", "M6", "M7" etc.)
… stands for "Messucher", which is German
for "Viewfinder". The "3" in M3 was chosen
because of the three bright line finders for the 50, 90 and
135 mm lenses. Later the numbers of the M cameras were more
or less chosen to follow each other.
"Meßsucher". It is always correctly written
with the "ß". There are technically not three
"s", rather the "ß" and one "s"
because it is a word constructed by the combining of two precise
words.
M-body evolution in chronologic order:
M3 - MP - M2 - M1 - MD - MDA - M4 - M5 - CL - MD-2
- M4-2 - M4-P - M6 - M6 TTL - M7 - MP.
MP
Stands (also) for Mechanical Perfection.
Noctilux
Refers to the maximum lens aperture - here f1.0 . "Nocti"
for nocturnal, "lux" for light.
RF
(R)ange (F)inder - the mechano-optical mechanism which allows
M Leicas to focus.
Alternative meaning - RF is also shorthand for Hexar RF ,
Konica's motorised "M-lens-compatible" rangefinder
camera released in 2000.
Summarit
Refers to the maximum lens aperture - here f1.5 . Presumably
the name is a derivative of the root "Summicron"
name in the same way "Elmarit" was derived from
the slower "Elmar".
Summicron
Refers to the maximum lens aperture - here f2.0 . There are
many guesses how this name came about, the most popular being
that the "summi" came from "summit" (of
lens performance) while the "cron" came from "chroma"
(ie. for colour).
Summilux
Refers to the maximum lens aperture - here f1.4 . "Summi"
for "summit of performance" (same root as "Summicron"),
with "lux" added for "light" (ie. the
enhanced light gathering abilities).
Telyt
Lens nomenclature - short-hand for " telephoto "
TTL
(T)hrough (T)he (L)ens light metering, usually WRT the flash
metering capabilities built into the R6.2, R8, R9, M7 &
M6TTL cameras.
Vulcanite
The black rubberized, textured material used to cover Leica
camera bodies prior to the 1980s. It actually was made of
vulcanised rubber (hence the name) and was and remains much
loved by professionals because of its solid, sure grip (see
[ this topic ])
VF
(V)iew (F)inder - the eyepeice and associated optics you look
through in a camera.
Credit:
Thanks to www.nemeg.com for definitions.
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