Glossary of Leica Terms
[…] 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 corrected. , 
[…] 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. 
What happens to light when it moves through R series Leica SLR bodies. Light from the lens is split into two when it hits the reflex mirror — one portion 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 & viewfinder.
It's because of this "beam splitting" that you have to use Circular Polarizing filters on R cameras to obtain accurate light meter readings. With linear polarizer filters, phase cancellation effects occur when the light travels through the mirror, resulting in inaccurate and unpredictable readings.
An acronym for "(C)lean, (L)ubricate & (A)djust", where the item is re-lubricated, fine-adjusted and calibrated rather than extensively repaired.
Refers to the maximum lens aperture — here ƒ3.5. Historically derived from the original 1925 50mm ƒ3.5 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 ƒ3.5 Elmar superceded the Elmax, which was discontinued due to its complexity and high cost of manufacture. 
Refers to the maximum lens aperture — here ƒ2.8. The name is obviously derived from the earlier (and slower) "Elmar" designation. Mind you, not every ƒ2.8 lens is called an "Elmarit". The most obvious exception being the 50mm ƒ2.8 Elmar-M lens, which for nostalgic and marketing reasons has kept the original 1930's "Elmar" designation (the 50mm ƒ3.5 collapsible Elmar, manufactured 1930-59, was one of Leica's most famous and popular lenses).
Refers to the maximum lens aperture — usually ƒ2.5. The name was apparently taken from the name of lens designer Professor Max Berek's dog(!). 
A compound word derived from "(Lei)tz" and "(ca)mera". Apparently they were going to use "LECA", but a French camera manufacturer already used a similar name, so they inserted an 'i' to prevent any confusion or trademark disputes. 
Brief overviews of the company's history can be found here and here. If you were wondering why people would still want to use Leica cameras at all, especially in this digital day & age, see this amusing April 2003 discussion at <Photo.net: #004w7W>
(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. 
Actually, the correct translation should really be "Rangefinder". "Viewfinder" (or "finder") is in fact the second part of the word, "Sucher". 
"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. 
Correction — since August 1st 1998, we have a new spelling in Germany. You now have to use three "s" instead of the "ß" plus "s". On the German Leica Website it now says Messsucher(!) The spelling is valid in Germany except for schools in Schleswig Hostein and writers at the Frankfurter Allgemeine Zeitung (FAZ), which means there's a lot of confusion now. 
Refers to the maximum lens aperture — here ƒ1.0. "Nocti" for nocturnal, "lux" for light.
(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 (see this FAQ topic).
Refers to the maximum lens aperture — here ƒ1.5. Presumably the name is a derivative of the root "Summicron" name in the same way "Elmarit" was derived from the slower "Elmar".
Refers to the maximum lens aperture — here ƒ2.0. 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).
Refers to the maximum lens aperture — here ƒ1.4. "Summi" for "summit of performance" (same root as "Summicron"), with "lux" added for "light" (ie. enhanced light gathering abilities).
Lens nomenclature — short-hand for "telephoto"
(T)hrough (T)he (L)ens light metering, usually WRT the flash metering capabilities built into the R6.2, R8, R9, M7 & M6TTL cameras.
The black rubberized, textured material used to cover Leica camera bodies prior to the 1980s. It was actually made of vulcanised rubber (hence the name) and remains much loved by professionals because of its solid, sure grip (see this FAQ topic)
(V)iew (F)inder — the eyepeice and associated optics you look through in a camera.
The irrational belief that the wider your lens aperture, the closer you are to Aesthetic Purity. For these blokes a ƒ2.8 lens is always trumped by a ƒ2.0, which in turn is beaten by a ƒ1.4, which inevitably loses out to ƒ1.0 (see "Noctiloonies" below).
"BFA" is an acronym for "Bachelor of Fine Arts" — the dregs of undergraduate life transformed into a Post-Modern Committee for the Protection of Aesthetic Virtue & Prevention of Creative Vice.
Although they claim to champion artistic innovation and tolerance, the reality is anything but. Patrolling discussion forums in their endless spare time, they never fail to stifle any criticism of Approved Artists (Arbus, Gibson, Goldin, Eggleston et.al.) with hysterical shrieks of "Philistine!", "Sexist!" or "Racist!".
Of course it's all just a smoke-screen. What they're really on about is revenge for the humiliation they suffered as undergrads, from everyone else who actually studied for real degrees.
A subset of "Street Photography", where the photographer is so cowardly (or creepy) that they only take photos of people from behind — often only of people's behinds.
Post-purchase feelings of guilt when you realise the "lens you really needed" cost as much as a small car. For married couples it usually leads to "Price Cloaking" (see below).
A derogatory term for a camera owner more interested in their camera as shiny artefact than photography.
A derogatory term for people who keep their cameras and lenses really, really, really clean.
Acronym for David Alan Harvey, Magnum photographer, (b.1944). Famous contributor to National Geographic Magazine — in particular "Barcelona" (NGM December 1998, p.42-59) and "Cuba" (NGM June 1999, p.4-45).
"Film is dead and I've been told it'll be discontinued in six months!" "My DSLR paid for itself twice over before I even left the store!" "Every photojournalist now uses digital, so if you're serious about your photography then you better get with the times."
Ho-hum. We've seen them on every mailing list and online forum. A marketer's wet-dream. They genuinely cannot tell the difference between Butter and Engine Oil. Slop any rubbish into their bowl and they gobble it down. "Hmmm, Digital! Yum! What's next?…"
A person for whom the solution to every conceivable problem is "Keep It Simple Stupid". Examples: "My shots suck!" "KISS." "There's a hole in the Ozone Layer." "KISS!" "I have non-Hodgkin's Lymphoma." "KISS (your backside goodbye)."
Lens Dust Anxiety
The irrational fear that the speck of dust between the 6th & 7th elements in you APO-Elmarit will so deteriorate your images that they will look like they were only taken with a Nikon.
The mindless twit who quotes 30 preceding messages in a thread to only add "I agree".
Blundering Clumsiness dressed up as Art. The kind of lazy, random, compositionless, wildly-tilted nonsense where the photographer shows a level of expertise equivalent to that of an ape with a camera strapped to its head. Derived from the Late Night Monkey Cam segment on the David Letterman TV Show.
Spec-junkies who spend all their time obsessing over the MTF lens charts at Photodo.
A person so dazzled by the amount of glass in their ƒ1.0 optic, that their judgement has become as blurred & fuzzy as the images from their beloved lens.
The photo.net Leica Forum equivalent of PAW. An appropriate term — usually the photography is so inept and self-indulgent that the viewer is left speechless.
Acronym for Picture A Week. Originally it was Picture A Day, but many found this too onerous, so it was slackened to Picture A Week. Although the idea behind PAW is noble ("Don't just sit there stroking your camera, go out and shoot something!"), over time it has deteriorated into a dreary parade of grainy, B&W, poorly framed & composed, cat/ butt/ brat & empty-doorway snaps.
Another unintentionally appropriate term. Surely it's no co-incidence that PAW is the homonym of "poor".
Star-struck photographers so paralysed by their uncritical adulation of Photo Heroes (Winogrand, Frank, DAH, Nan Goldin, Ralph Gibson et. al.) that they never quite manage to take any photographs themselves.
The artful concealment of the true purchase price of a lens or camera from one's spouse or girlfriend. "Did You Buy Another #$%!ing Camera!" "What this thing? It only cost… $300!" When encountering PC, it's safe to assume the stated price is < 0.2x of the actual amount.
The mechanism used by USA Leica dealers to charge exactly the same price for Leica equipment. See this discussion elsewhere in the FAQ.
A person with unshakable faith in the camera & lens "scientific reports" of Erwin Puts.
Recent Leica M and R cameras have a small red circular logo with the word "Leitz" or "Leica" inscribed in italic script. "Red Dot" is the shorthand used to describe these red branding badges.
Insecure R8 owner who tries to pre-empt any criticism of his (controversial) camera by endlessly singing its praises.
Regret and longing for the camera/lens "you never used" (and thus sold). A common affliction, often leads to buying exactly the same camera/lens a few months later for hundreds of dollars more.
Wind-bags who bomb mailing lists with scores of posts a day, in the unshakable belief that the world was created solely as an audience for their opinions.
The noble tradition of candid people photography by the likes of HCB or Kertész or (early) Winogrand, given a Post-Modern death kiss.
At best it nostalgically recreates the work of past greats. At worst, it's merely an exercise in "Butt Photography" or "Monkey-cam" (see above).
A Leica user (typically a collector) convinced that only those cameras made in Wetzlar Germany prior to 1974 are worth a damn.
The camera-owner's inverse of blokes bragging about their penis size, where the one with the shortest focal length wins. "You shot that with a 21mm? Hah! Look at this one, I took it with a 15mm!"
( More Terms eventually… )