Camera, Lens and Gear:Pentax lens jargon

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This page is a chapter in the book Pentax Specific Information.
AL (Aspherical Lenses)
Contrary to spherical, aspherical lenses do not have a uniformly
curved spherical shape. The form of an aspherical lens is adapted to a specific
task and the curvature of each is individually computed. The production of these
lenses is accordingly complex. The greatest advantage of aspherical lenses: several
types of optical aberrations can be corrected at one time. They are used particularly
in high-quality lenses allowing for the use of fewer lens elements so that a high
luminous intensity is attained.

ED Glass
Normal glass lenses tend to divide the incident light into its various colour components,
as a prism would do. This happens particularly at the edges, adding unwanted
colour fringing to the photo. The longer the focal length of the lens the more
apparent is the fringing effect. ED glass is an exceptionally high-quality special glass
that prevents this so-called chromatic aberration to a very great extent.

IF (Inner Focusing)
Each lens is composed of several groups of lens elements. With
an Inner Focusing design only one of these groups is moved. Inner Focusing brings
a number of advantages compared to a conventional focusing design where all the
lens groups are moved: it works faster and the overall length of the lens remains
unchanged so the centre of balance remains constant. Additionally, since the front
lens element doesn’t rotate, filters do not have to be readjusted every time the focus
point changes.

Limited Edition
“Limited Edition” is the PENTAX lens series that is characterised by extremely high
quality standards. Since more expensive materials are used and a complex production
process employed, PENTAX manufactures a restricted number of the “Limited
Edition” lenses on a daily basis.

SDM (Supersonic Direct-drive Motor)
Small motors manage the actual focusing of an autofocus
system. With the “Supersonic Direct-drive Motor” PENTAX has developed
a technology that propels the focusing procedure with an ultrasonic motor. PENTAX
SDM lenses drive the autofocus system significantly faster and operate more quietly
than conventionally driven AF lenses.

smc (super multi coating)
Super multi coating is the benchmark of all PENTAX lenses.
smc describes a high quality coating of the lens elements that consists of seven microscopically
thin layers. The normal light loss at the lens surface between air and glass
is reduced from 4 % to 0.2 %.

The designation is for lenses designed specifically for PENTAX digital SLR cameras.
They are not compatible with 35mm film SLRs.


The latest generation of lenses for use on all PENTAX digital SLR cameras. They
utilize the “Supersonic Motor” technology compatible with the appropriate cameras
(K10D) and are weather and dust-protected. They are not compatible with 35mm
film SLRs.

This designation is used for lenses that are optimized for digital photography but can
also be used with 35mm SLR cameras.

smc-FA and FA*
* Autofocus with screw drive system
* Aperture ring
* Automatic aperture setting is available
* Certain zoom lenses feature the power zoom function
* Image format covered: 24mm x 36mm
* Suitable for APS-C digital sensor format and 24mm x 36mm film format
* Sub-groups: FA* and FA Limited series
* In production: Only five of the original 42 lenses are still in production (as of May 2010)

The FA series lenses are autofocus and allow for certain modern cameras (film and digital) to automatically
set aperture (Tv mode), shutter speed (Av mode), or both (Program mode). You can also set exposure
manually if the camera body allows for this. On recent camera bodies (e.g. *ist and all digital SLR cameras)
you use dials on the camera body to set the aperture value
(the aperture ring on the lens must be in the "A" position at all times).
On older models (such as ZX-5N, MZ-5N, LX, ME, MX, K1000) the aperture is set with the aperture ring on the lens.
Three FA "Limited" lenses were made available in 2001.
Except for these and the 35mm f/2 and 50mm f/1.4, the FA series, which consisted of 42 lenses total, has been discontinued.
The FA series also includes 11 "star" lenses (FA*) that employ the finest of Pentax optical and mechanical engineering.
The smc 600mm FA* special is the longest Pentax lens available via special order.

SP (Super Protection)
Super Protection coating is a special coating of the front lens element of particular
PENTAX lenses. It is based on a fluoride bonding and prevents the contamination
of the lens by water-based or oily substances. SP coated lenses are much more
easily cleaned of finger marks, smears or other matter than may come in contact
with the lens.

WR (water resistant)
These lenses are designed to work with weather sealed DSLRs such as the K10, K20, K-7
and K-5 giving the ability to photograph in wet condition (not underwater).

Older series lenses

smc-FA J
* A small series of 3 autofocus zoom lenses
* Automatic aperture setting is available, but there is no aperture ring

smc-FA J lenses lack the aperture ring but otherwise work like an FA lens set permanently to the “A” position.
Due to the lack of an aperture ring these lenses cannot be used on camera bodies where use of an aperture ring is mandatory
(such as LX, ME, MX, K1000), but can be used on e.g. the ZX-5N in Program and Tv mode.
These lenses provide full functionality on all recent bodies like the *ist, *ist D series and K (digital) series

* First generation autofocus lenses
* Automatic aperture setting is available
* One zoom lens features the power zoom function*

Lenses in this series work just like FA lenses; see above for features and limitations.
The F series consisted of 20 lenses is now fully discontinued.
The F series also includes 3 "star" lenses (F*) that employ the finest of Pentax optical and mechanical engineering.

* The third generation of manual focus lenses
* Automatic aperture setting is available

smc-A lenses are manual focus. Regarding exposure control they work like FA lenses.
The A series also includes 9 "star" lenses (A*) that exemplify the finest in Pentax optical and engineering.

* The second generation of manual focus lenses (generally smaller than K lenses)
* Manual aperture

smc-M and smc (commonly know as "K") lenses are manual focus and have no "A" setting on the aperture ring.
These lenses allow for the camera to automatically set shutter speed (if it has the Av auto-exposure mode).
You can also set exposure manually if the camera body allows for this.
The ZX-5N is an example of a body which provides Av mode as well as manual exposure mode with M and K lenses.
Almost all K and M lenses have an automatic diaphragm.

Some recent bodies cannot use M and K lenses or only with some limitations. An example are the *ist D and K (digital) series.
In M mode you set the aperture using the aperture ring on the lens; the camera will set the shutter speed when you
press the green button (or AE-L button if the camera has no green button).
Or you can set the shutter speed manually (there is no exposure read out in the finder to assist you).

The M series includes a single "star" lens (M*) that exemplifies the finest in Pentax optical engineering. That is the smc PENTAX-M* 300mm F4.

* The first generation of manual focus lenses
* Manual aperture

From Big Red:

You also have the Takumar Bayonet lenses which are the cheaper version with less optical coating.

Also the DA-L lenses with plastic mounts

great source of info on Pentax here

K: the original K-Mount lenses, full 35 mm frame coverage, made out of metal, extremely solid and well constructed, great mechanical feel. Capable of only manual metering and aperture priority
M: like the K-series, but generally smaller and lighter
AF: like the M series but, but with an AF motor in the lens
A: like the M series, but with an "A" setting on the aperture ring, thus supporting additionally shutter priority and program operation
F: like A series, but supporting modern-age auto-focus (AF motor in the camera body) and digital communication with the camera body
FA: further development of the F-series, more extensive communication with the camera body
FAJ: like FA lenses but without an aperture ring, thus only operable on bodies that can control the aperture electronically
DA: like FAJ, but optimized for digital bodies and covering the image circle of the reduced-size digital sensor
D FA: like FA, but the optics are optimized for both film and digital
DA L: like DA, but featuring a very light construction, thus optimally paired with very compact and light bodies like the K-m
General Terms
*: the star sign follows the lens series designation (e.g., A*, FA*), and denotes a high-performance lens that uses special-glass elements.
Limited: Similar to the * designation in that the lenses are of very high quality, but not meaning that the lens is being produced in limited quantities. Star-lenses are generally large and expensive zooms and Limited lenses are generally compact and expensive primes with not very wide apertures.
AL: a lens that uses one or more aspherical elements (aimed at achieving flat field and corner sharpness with wide-angle lenses).
ED: a lens that uses extra-low dispersion glass elements (aimed at reducing color aberrations in telephoto lenses).
IF: a lens that uses an internal focusing mechanism (lens groups are being moved with respect to each other instead of the entire optical assembly being moved towards or away from the film plane); IF is typically used for longer lenses with large front elements in order to reduce power requirements for the focusing motor and to make such lenses easier to use with polarizing and graduated filters. IF lenses typically change their focal length slightly during focusing. They get wider as they get focused closer.
Fixed Rear Element Extension (FREE): a lens whose last cell i remains fixed during focusing. FREE lenses achieve low field curvature and low spherical aberrations not only when focused close to infinity but also at very short distances. For normal applications the FREE system leads to small physical extensions, and thus allows the design of physically smaller and lighter lenses. For macro applications FREE lenses exhibit non-proportionately long extensions which aid precise focusing. However, to achieve these positive effects, the FREE design causes the lens focal length to decrease as the focus distance decreases. Pentax has listed FREE as a feature only for prime lenses even though there are zooms that also have a fixed rear elements (e.g., SMC-A 70-210/4, SMC-A 28-135/4).
Weather-Resistant (WR): a lens that features special seals and is thus resistant to dust and light rain.
Previous: Camera, Lens and Gear:Manual K and M42 mount lenses on K-5, K-7, K-x, K-m, K20D/K10D, K200D/K1x0D, *ist Dx etc. Pentax Specific Information Next: Camera, Lens and Gear:Pentax Firmware

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