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Glossary of mFT terms

Camera maker Olympus and sensor manufacturer Kodak created the Four Thirds standard as a means of providing an imaging system that was designed from the ground up for digital photography. In particular, tele-centric lens design was intended to explicitly accommodate the requirements of digital sensors for orthogonal light reception. Other objectives were interoperability within the open standard, as well as light weight and compact equipment size.

mft

As a side effect of the launch of the FT-system in 2003, a whole new set of terms and acronyms was born. Then in 2008 when Panasonic released the G1 as the first Micro Four Thirds camera, the system-specific terminology became even more complex, so that it now ranges from Anti-Shock to ZERO-Coating. The listings and explanations below aim to cut through this jargon and help users to better understand and appreciate their mirrorless camera and lens system.

If you think that there is an important entry missing, please let me know. And if you can already provide a tentative definition, that would be even better. Just drop me a note by email and I will add the new term to the listing. Thanks in advance for your help!

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2x2 Control Dial:
2x2 Control Dial
2x2 Control Dial on an E-M1
The 2x control dial is a lever on the back of selected Olympus camera that changes the functionality of the front and rear wheels. The handling feature was first introduced on the PEN E-P5 and subsequently also implemented on some OM-D models. The locking lever, which can be moved by thumb between positions 1 and 2, lets photographers switch between two customizable functions each of the front and rear dials. These wheels can then be used to quickly adjust a total of four different camera settings, such as aperture, exposure compensation, ISO, and white balance. The assigned settings control will normally vary by PASM shooting mode. The 2x2 Control Dial represents a very convenient way of quickly operating a camera, without the need to take the eye off the viewfinder or to delve into the menu.
4K Photo:
4K Photo is an operating mode on selected Panasonic mFT cameras that lets photographers extract single frames from 4K recordings. 4K Photo is different from simply grabbing a simple image from video footing by making it possible to select a still image-friendly aspect ratio, choosing aperture and shutter speed values optimized for still capture, and providing full EXIF information for the individual image. The operating mode is particularly useful for capturing the "decisive moment" of fast-moving subjects.

A

Anti-Shock:
mft
Anti-Shock mode on an E-P5
Anti-Shock is an Olympus term, which was originally used for a mirror lock-up mechanism to reduce vibration from the mirror swing on Four-Thirds DSLR. On mirrorless m43 cameras, the term refers to a delay between the shutter closing and it opening, allowing for time for the vibrations caused by the shutter movement to die out and, thus, eliminating the risk of image blur. Selected cameras also feature a "0 Sec Anti-Shock" setting, whereby the camera uses its electronic rather than its mechanical shutter for first curtain operation at certain shutter speeds. Electronic shutters do not rely on any moving parts, whose deceleration could cause vibrations. Hence, electronic shutters are not subject to the adverse effects of shutter shock.

D

Decoration ring:
Decoration rings are available as accessories for certain Olympus mFT lenses. They attach to the lens via the bayonetts of the lens hood or tripod mount adapter, when the latter are not in use. Decoration rings provide a smoother appearance to the lens and, in some cases, make it possible to add a color accent. Moreover, decoration rings that cover the studs of the tripod mount adapter, such as the Olympus DR-66, can help to avoid irritation when shooting hand-held.
DFD – Depth from Defocus:
Depth from Defocus is a Panasonic-technology, first introduced in the GH4, to improve autofocus tracking of moving subjects. DFD calculates the direction and the amount to move the focus lens based on two images captured with different depth of field in connection with knowledge of the bokeh characteristics of the attached lens. This information makes it possible to jump to the new focus point in a single movement, instead of the gradual and slower "trial and error" method of standard contrast-detect AF systems. However, the technology only works with Panasonic lenses, as DFD is not part of the Four Thirds standard.
Dual IS (Image Stabilization):
Dual-IS is a handshake correction system introduced by Panasonic with the Lumix GX8 that combines lens-based OIS technology with sensor-shift, body-based stabilization. According to Panasonic, their O.I.S. lenses correct for two axes of motion, while their sensor shift mechanism compensates for four. The combination of the two systems yields stabilization across all five axes of motion. Panasonic claims that Dual-IS on the GX8 is 3.5x better at wide-angle and 1.5x better at telephoto compared with the stabilization provided in the GX7. Most lenses with Mega-OIS or Power-OIS that were released prior to the GX8 can be updated to support the Dual-IS functionality via firmware (the exceptions are the 14-45mm, 45-200mm, and 100-300mm).
Dual VCM (Voice Coil Motor):
Dual-VCM is a focusing system introduced by Olympus with its 40-150mm f/2.8 PRO zoom. It is based on the separation of the focusing lens elements into two VCM groups that are simultaneously controlled by their own linear-drive motor to produce extremely quick, quiet, and precise focusing. Voice coil motor systems are based on rectilinear motion, with the coil being the only moving part. This makes it possible to achieve high-speed autofocus and accurate positioning with virtually no sound. Dual VCM represents an evolution of the Movie and Still Compatible mechanism in earlier Olympus lenses.

E

Equivalent focal length:
Equivalent focal length is a measure that indicates the corresponding angle of view of a lens and sensor size combination, expressed in terms of the traditional 35mm film format. A given lens mounted on a camera with a small sensor will generate a narrower angle of view than the same lens used in combination with a full frame 35mm format camera. Hence, in order to get a similar angle of view, the photographer has to use different focal lengths on small sensor and full frame sensor cameras. The diagonal of the Four Thirds sensor is half as long as the diagonal of a full frame 35mm sensor, giving rise to a format factor or 2. The equivalent focal length of a (m)FT lens, thus, is half as long as a given full frame lens in order to yield the same angle of view. For example, a 25mm lens on a Micro Four Thirds camera has the same angle of view as a 50mm lens on full frame. A secondary dimension of equivalence concerns depth of field. As its equivalent focal length is shorter, mFT provides deeper DOF. Equivalent depth of field can be calculated by multiplying the aperture value used on a small sensor camera by the format factor. For example, a 1.4/25mm lens on mFT is equivalent in both focal length and DOF to a 2.8/50mm lens on 35mm full frame.
ESP – Electro Selective Patterns:
ESP is a Olympus-specific metering method that meters the brightness of the center and the surrounding areas separately. In recent cameras, ESP meters exposure in more than 300 areas of the frame and optimizes exposure accordingly. For example, metering gives priority to any faces that are being detected. Olympus recommends the use of ESP for general use.
EVOLT:
Evolt is a marketing designation for non-professional DSLR cameras that was used by Olympus in North America up to 2007. The E-410 and E-510 were the last cameras marketed as EVOLTs. There had been three EVOLTs earlier (E-330, E-500, E-300), bringing the total to five (the E-400 was only sold in Europe).

F

FAST (Frequency Acceleration Sensor Technology):
FAST is a Olympus autofocus tracking system introduced with the PEN E-P3. The FAST chip reads image data off a large number of separate focus points spread over nearly the entire sensor. This is achieved at a speed of 240 frames-per-second, which leads to shortened image blackout in the viewfinder and enables photographers to better track fast action.
Focus Stop Buttons:
Focus stop button
Focus Stops on ZD 150mm
Focus Stop Buttons are controls on selected Olympus Four Thirds lenses to temporarily deactivate autofocus operation, so as to maintain focus at the point where the button was pressed. The Focus Stop Buttons, thus, make it possible to prevent the auto-focus system in C-AF mode from adjusting to foreground movement, after correct focus on the primary subject has been achieved. Three Super High Grade optics (Olympus ZD 35-100mm, ZD 90-250mm, and ZD 150mm) are equipped around the front end of the lens with four Focus Stop Buttons each. All of these buttons have the same effect. The (single) L-Fn button on some Olympus mFT lenses can perform the same functionality, if set in the camera menu to AF-stop (which is its default).
FP-TTL – Focal Plane-Through The Lens:
FP-TTL is an Olympus flash mode that makes it possible to use flash at high shutter speed, notably for fill-in portraits in bright sunlight. The flash fires multiple pulses in coordination with the movement of the shutter, such that the entire focal plane gets illuminated, even as the shutter speed exceeds the camera's sync speed. Similar features at other manufacturers are often labeled as High Speed Synchronization.
FT – Four Thirds:
four thirds standard
Origin of Four Thirds[dpnow.com]
Four-Thirds is an open standard for a digital camera system that is centered on a sensor, whose size corresponds to the imaging area of a video camera tube of 4/3 inch diameter. The size of the video tube inspired the name for the FT standard. The 18 mm x 13.5 mm sensor used in Four-Thirds and Micro-Four-Thirds cameras happens to offer an aspect ratio of 4:3. Its diagonal (22.3mm) is half the size of a 35mm full frame image receptor, giving rise to a format factor of 2. The Four-Thirds lens mount is about twice as large as the diameter of the image circle, which makes it possible to produce lenses for the system that are telecentric and offer even contrast and sharpness across the entire image frame. Moreover, the standardized mount creates the possibility for photographers to freely combine interchangeable lenses and cameras from different manufacturers that adhere to the standard.

H

HD Video Support:
HD Video Support is a feature of many Panasonic mFT lenses implying quick and quiet autofocus operation and smooth aperture change during movie recording. As a result, continuous AF tracking is available during video capture, no operating noise is being picked up on the audio track, and no sudden jumps in exposure occur when the aperture changes. Similar to the MSC mechanism in Olympus lenses, Lumix optics with HD Video Support use an inner focus, direct-drive, linear motor for focusing action.
Hidden Menus:
Hidden menus are sections of camera memory that contain information for Olympus and Panasonic service personnel, such as errors that the camera's operating system has encountered. One piece of very useful information that the hidden menus reveal is the number of shutter actuations the camera has performed so far. Separate instructions on how to access this shutter count information are available for Four Thirds, Olympus mFT and Panasonic mFT cameras. More information on how to interpret the hidden menus is contained in the camera's service manual (see, for example, the respective Panasonic pdf downloads).
HG – High Grade:
High Grade is a designation of a dust and splash proof series of Olympus FT lenses aimed at enthusiast photographers. The set comprises 6 zooms and 4 prime lenses. The 2.8-4/12-60mm, 2.8-3.5/50-200mm and the 2/50mm Macro were particularly appreciated by FT-shooters for their very good imaging performance, while being relatively compact and accessibly priced. At times, these three HG optics were referred to as the "Holy Trinity of Four Thirds". – In some countries, the lens series was called "Pro Grade" instead of HG.
Hybrid-OIS (Optical Image Stabilization):
Hybrid-OIS is a system to reduce the adverse consequences of camera shake during movie recording, introduced by Panasonic initially in some of its camcorders and then also in its cameras (first in the Lumix GX8). Hybrid-OIS provides video stabilization across all five axis of movement. This 5-axis stabilization is achieved by combining lens-based OIS, which can adjust for movement along up to four axis (horizontal, vertical, yaw and pitch), with electronic stabilization, which in the case of Hybrid-OIS corrects for movement around the lens axis ("roll").

I

IBIS – In-Body Image Stabilization:
olympus 5 axis ibis
Olympus 5-axis IBIS
IBIS is a system to reduce adverse impacts of camera shake by shifting the sensor in such a way as to counteract the motion of the camera. Olympus introduced image stabilization with their E-510 Four-Thirds camera, employing a system built around their Supersonic Wave Drive, and Panasonic first included IBIS in their GX7. The early implementations of IBIS shift the sensor around two axis: pitch and yaw. In 2013, Olympus introduced the E-M5, which features 5-axis IBIS, counteracting movement in terms of horizontal shift, vertical shift, rotary motion, as well as pitch and yaw. The system is highly effective and can make it possible to shoot blur-free images handheld at shutter speeds that are 4-5 times longer than would otherwise be possible. IBIS can, of course, only counteract camera shake-related movement, but not any movement in the imaging subject itself.
Imager AF:
Imager AF is an autofocus technology that uses the imaging sensor to achieve focus with Olympus mFT cameras and lenses. It is also available in Olympus FT cameras and lenses released since 2008. The Imager AF technology uses contrast detection to secure focus.

L

L-Fn button:
L-Fn button
The L-Fn button
The L-Fn button is a control on selected Olympus mFT lenses that can be configured through the camera's setup menu. Once the menu option has been assigned, pressing the L-Fn button activates the preselected menu option. Hence, the button acts as a shortcut to the selected imaging feature. The default function of the L-Fn button is AF Stop, which temporarily suspends continuous autofocus when an object suddenly appears in front of the lens. Another popular choice is to use the button to activate the digital teleconverter, so as to enlarge the center portion of the image. The menu option selected for the L-Fn button does not have to be any specific lens function, though, but can equally alter general camera settings, such as white balance or the use of the HDR function.
Leica D/DG:
panasonic leica 25mm ft mft
Leica Summilux 25mm (mFT & FT)[omuser.com]
Leica D and DG are designations for a series of premium lenses from Panasonic. All Four-Thirds lenses sold by Panasonic (three zooms and one prime) were Leica D optics, and several Leica DG lenses have over time become available for Micro Four Thirds. Every D or DG lens carries a Leica lens-speed designation, like Nocticron, Summilux, or Elmarit. It is understood that the lenses are designed and produced by Panasonic, but submitted for approval to Leica with respect to their optical characteristics and manufacturing tolerances. Hence, Panasonic-Leica lenses are required to meet a set of demanding quality standards established by the German company, but are otherwise the result of Japanese optical manufacturing excellence. The close cooperation between the two companies on the D/DG lenses has also had a positive impact on the technology and quality in other camera and lens system areas of the partners.
LUMIX:
Lumix is the brand name used by Panasonic for its cameras and lenses. The company claims that the term Lumix is derived from a combination of "luminance" and "mix", with the latter referring to the joining of Leica's optical know-how with Panasonic's expertise in electronics. This collaboration is said to have created a quality in imaging that none of the partners could have achieved on their own.

M

M.ZD – Micro Zuiko Digital:
M.ZD is the designation of Olympus Micro Four Thirds-lenses. The company categorizes its optics into three series: M.Zuiko (standard) is a set of lenses that features compact and lightweight construction, M.Zuiko Premium consists of an array of fast, elegantly designed primes, and M.Zuiko PRO is a range of weathersealed, fixed maximum aperture lenses dedicated to professionals.
Mega-OIS (Optical Image Stabilization):
Mega-OIS is a lens-based system to reduce the adverse impacts of camera shake, used by Panasonic and Leica in some FT and mFT lenses. The feature was introduced with the very first FT lens from Panasonic, the Panasonic-Leica 14-50mm f/2.8-3.5. In practice, Mega-OIS provides a stabilization benefit of about one stop, so that an image that could be taken blur-free at 1/15 sec without stabilization, could be taken at 1/8 sec if Mega-OIS is turned on. The subsequently released Power-OIS system is more effective, particularly at low shake frequencies.
mFT (or m43) – Micro-Four-Thirds:
four thirds mft mount
The FT and mFT mounts compared[panasonic]
Micro-Four-Thirds is an imaging system standard that is based on the same sensor size and optical principles as Four Thirds. However, mFT uses a shorter flange-to-focal-plane distance, a slightly smaller lens mount diameter and two additional electrical contacts for high-speed data transmission. As a mirrorless system, mFT does not need to accommodate a mirror box in the optical path, so that the camera bodies can be build slimmer than those of DSLRs. Further reductions in size for both cameras and lenses are made possible with the narrower mount and the shorter focal-plane distance. Finally, the increase in the number of electrical contacts in the mount from 9 to 11 facilitates information transfer between camera and lens for data-intensive video shooting. Micro-Four-Thirds is an open standard, and the number of participating companies has increased substantially over time.
MSC – Movie and Still Compatible:
olympus msc
MSC Mechanism[olympus]
MSC is a mechanism in most Olympus Micro Four Thirds lenses to enable fast and quiet autofocus during still image capture and movie shooting. The Movie and Still Compatible module is part of the inner focusing system that adjusts focus by optimally displacing only one or a few lightweight lens elements. The focusing element is moved alongside a metallic shaft using a precision-finished feed screw. There are no gears involved, which in traditional AF systems cause operating noise that is particularly detrimental during video capture with an in-camera microphone. MSC, thus, enables smooth autofocusing with high speed and ultra-low noise for both still and movie shooting. Lenses made by Panasonic that are labelled to provide HD Video Support have a similar design and offer the same functionality of fast and silent focusing operation.

N

NSC – Nano surface coating:
Nano surface coating is a coating technology used by Panasonic on newer mFT lenses to reduce ghosting and flare. It consists of an extra-low refractive index coating with nano-sized structure. Panasonic claims a dramatic reduction in reflections across the entire visual light range.

O

OM-D:
OM-D is the designation of Olympus mFT cameras with an integrated, centrally-located viewfinder. The design of the OM-D cameras with a large, angular viewfinder housing makes reference to the company's analog OM Series, which started with the OM-1 back in 1973. Three lines of OM-D's have been launched that differ in features and size: The (relatively) large E-M1 is weathersealed and features a sensor with phase-detect pixels, so that it can autofocus legacy FT lenses as quickly as an FT camera. The mid-level E-M5 is equally sealed against dust and moisture, but relies exclusively on contrast-detection for autofocus. Finally, the compact E-M10 also uses contract-detect autofocus, but does not feature any weathersealing.

P

PEN:
PEN is the brand name for Olympus rangefinder-style mFT cameras, reminiscent of the half-format cameras marketed by the company from 1959 to the early 1980s. The PENs feature a stylish metal finish for their small-sized bodies. In addition to the main line of E-P cameras, Olympus also released a E-PL (PEN Lite) range and a E-PM (PEN Mini) series, which are more compact and have a simplified interface without control dials.
Pixel mapping:
Pixel mapping is an Olympus function to ignore dead or stuck pixels. When a user launches the pixel mapping function through the camera's menu, a firmware algorithm searches for individual photodiodes that are dead (always black) or stuck (always white). If such pixels are found, an interpolation procedure explores the pixels around the dead or stuck pixel, maps their locations, and inserts estimates for the data the misfunctioning pixel should be delivering.
Post Focus:
Post Focus is a feature on selected 4K-capable cameras from Panasonic that lets photographers chose the point of focus after an image has been taken. Post Focus makes use of Panasonic's DFD technology, while shooting sequences of 4K-video at 30p. The feature works by continually adjusting the focus point in each of the 4K frames. The photographer can then ex-post select the area on the image that should be in focus, and the camera will compare the frames it captured before putting forward the one in which that chosen area is best-defined.
Power-OIS (Optical Image Stabilization):
panasonic power vs mega ois
Power and Mega-OIS compared[panasonic]
Power-OIS is a lens-based system to reduce the adverse impacts of camera shake, used by Panasonic in some mFT lenses. Power-OIS is more effective at suppressing lower hand-shake frequencies than the earlier released Mega-OIS. In particular, Panasonic states that Power-OIS is very good at compensating for vibration caused when pressing the shutter button or when shooting in low light with slow shutter speeds. In practical tests of the Lumix 1.7/42.5mm Power-OIS, the system delivers a benefit of about 3 stops in shake compensation, so that a blur-free image taken hand-held at 1/80 sec without stabilization, could be taken at 1/10 sec if Power-OIS is activated. Lenses that have Power-OIS can be updated via firmware to support Dual-IS in more recent Lumix cameras that combines the in-lens stabilization with in-camera sensor stabilization.

S

SCP – Super Control Panel:
The Super Control Panel is an easy access grid that makes it possible to quickly change core settings on Olympus cameras. It is displayed by default on the camera’s panel display when using the viewfinder to preview the image for shooting, but can be customized to also show when using live view shooting. The Super Control Panel provides one touch access to functions like ISO, white balance, metering, sequential shooting, self timer, and focus mode.
SG – Standard Grade:
Standard Grade is the designation of an Olympus FT lens series developed for cost-performance and portability. Many of the lenses in this series were sold as part of camera/lens-kits. This includes the ZD 14-42mm f/3.5-5.6 and ZD 40-150mm f/4-5.6 lenses, which at the time of their launch were the world's smallest and lightest DSLR zooms for their respective focal length range. Unlike the HG and SHG optics, SG lenses are not weathersealed.
SHG – Super High Grade:
olympus shg
The six SHG lenses[olympus]
SHG is the designation of a fixed aperture, dust and splash proof series of Olympus Four-Thirds lenses that offers exceptional optical quality and is aimed at professional photographers. The set consists of four zooms, covering focal lengths from super wide-angle to super-tele, and two super-tele primes. The 150 f/2 and 300mm f/2.8 (nicknamed "Little Tuna and "Big Tuna" by Olympus enthusiasts) have particularly high resolving power and provide excellent sharpness wide-open, even when used in combination with the EC-20 2x teleconverter. The 14-35mm and 35-100mm SHG zooms have a maximum aperture opening of f/2, which at the time of release were the world's fastest zoom lenses for any interchangeable camera system. All SHG-lenses carry a platinum line on the lens barrel as a mark of distinction. – In some countries, the set of lenses is called "Super-Pro" instead of SHG.
Shutter Shock:
Shutter Shock is image blur caused by shutter vibration in mirrorless cameras. At certain shutter speeds – typically 1/20s to 1/200s – the movement of the shutter causes the camera body to vibrate, which leads to image degradation. The problem can be avoided by using the electronic shutter (if available) or the 0 sec Anti-Shock mode on newer Olympus cameras.
Simulated Optical Viewfinder (S-OVF):
olympus sovf
Backlit scene in S-OVF[olympus]
Simulated OVF is a setting on selected Olympus cameras that enables a view through the electronic viewfinder that is similar to what is shown in an optical viewfinder. In particular, S-OVF expands the dynamic range in the EVF, enhances shadow detail, and suppresses highlight blowouts. Hence, it becomes easier to frame and focus in backlit conditions, and the unprocessed display may help to better assess the shooting atmosphere in a dark environment. On the other hand, exposure compensation and white balance are not reflected in the display of the S-OVF. All data overlay options can still be displayed, but only those settings also typically found in optical viewfinds (shutter speed, aperture, ISO, and exposure meter scale) are active. The process of toggling the S-OVF on and off can be assigned to one of the function buttons for quick and convenient selection.
SSWF – Supersonic Wave Filter:
olympus sswf
Sensor assembly with SSWF[euyoung.net]
SSWF is a mechanism to protect the imaging sensor of (Micro) Four Thirds cameras from dust by vibrating a transparent filter that is located between the camera’s shutter and the sensor at an ultrahigh frequency of over 30,000 moves per second. The "dust shaker" consists of a circular glass panel, encompassed with a piezoelectric ceramic ring. The removed dust is retained in an adhesive retention area built in beneath the SSWF. Olympus included the SSWF-mechanism with its very first DSLR – the E-1 – which meant that Four Thirds users rarely had to undertake the dreaded task of cleaning dust particles off the sensor. Over time, other manufacturers caught on and developed similar in-camera dust removal systems, so that the technology has become a virtually universal feature on modern digital cameras.
SWD – Supersonic Wave Drive:
SWD is a fast and quiet autofocus motor used in some Olympus lenses. SWD uses an electric motor powered by ultrasonic vibration. The technology is similar to Panasonic's XSM autofocus system. Olympus claimed in 2007 that the new ZD 12-60mm F2.8-4.0 SWD lens then provided the world's fastest autofocus speed when mounted on an E-3.

T

Tatsuno Quality:
Tatsuno Quality is a quality standard for Olympus lenses named after the plant where the lens standards are conceived and formulated. Tatsuno is a city of about 20,000 inhabitants in the Nagano prefecture. This region, which is about 3 hours by car from Tokio, has a long tradition of precision engineering.
Tele-centric Lens:
olympus telecentric lenses
Telecentric lens design[olympus]
A tele-centric lens is an optic that produces an image from light rays that travel perpendicularly to the surface of the image sensor. Telecentric lenses eliminate the parallax error that occurs with standard lenses by having a constant, non-angular field of view. They always have the same field of view, irrespective of the focusing distance. Telecentric lenses offer high contrast and sharpness from corner to corner, and suffer less from chromatic aberration and shading of peripheral areas than traditional 35mm film lenses. The improvements in image quality are particularly pronounced for wide-angle lenses. Telecentricity is one of the core aspects of the Four Thirds system, and all native (Micro) Four Thirds optics are based on this approach to lens design. Telecentric design is facilitated through the relatively large diameter of the Four-Thirds and Micro-Four-Thirds mounts, which gives engineers the space to implement corresponding optical structures.
TruePic:
TruePic is the designation of the image processing engine used by Olympus in FT and mFT cameras. This digital system processor translates the information from the Bayer sensor into a color picture and performs noise reduction and image sharpening. Subsequent versions of the engine have offered improved imaging fidelity and operating speed. Panasonic cameras use the Venus engine.

V

Venus:
Venus is the name of the image processing engine used by Panasonic in its Lumix cameras. Similar to Olympus' TruePic, this set of microchips processes the signal from the imaging sensor to generate the colored image, reduce noise, and sharpen the final image. Over time, progressively better performing versions have been implemented in FT and mFT cameras.

X

X-lens:
X-lens is the designation of a series of Panasonic mFT premium lenses that feature power-OIS, nano surface coating, and special-glass lens elements. The group comprises the constant aperture f/2.8 zooms (12-35mm and 35-100mm), as well as the two 14-24mm and 45-175mm powerzooms. All X-lenses are suitable for High-Definition video recording.
XSM – Extra Silent Motor:
XSM is the designation of fast and quiet autofocus motors used in some Panasonic lenses, notably the Leica D Vario-Elmar 14-150mm f/3.5-5.6 Asph. OIS. Similar to SWD, XSM is based on supersonic oscillation. In addition to silent and seamless operation, the technology also provides high responsiveness, accuracy and focusing stability.

Z

ZD – Zuiko Digital:
olympus zuiko digital
The Zuiko Digital collection[olympus]
Zuiko Digital is the name of Olympus autofocus lenses for the Four Thirds-system. Between 2003 and 2008, Olympus introduced a total of 24 ZD lenses, of which 6 fall into the SHG, 8 into the HG, and 10 into the SG category. The word Zuiko means "light of the gods" in (ancient) Japanese, which doubtlessly makes for an attractive marketing term for a line of photography lenses. It also represents a reference to the Mizuho Optical Research Laboratory (in Japanese, the first character of the name "Mizuho" can also be read as "zui") where the company's first lenses were developed. Moreover, the corporate name before World War II, "Takachiho" means "mountain of the gods" in Japanese, and, thus, provides another root of origin for the choice of the lens designation. – Olympus calls its lenses for the Micro-Four-Thirds system M.Zuiko Digital.
ZERO – Zuiko Extra-Low Reflection Optical coating:
ZERO is the designation of the coating technology used on recent Olympus lenses. The ZERO coating is an application of thin layers of material on lens surfaces in order to reduce ghosting and flaring, and thus to obtain more contrast-rich and color-accurate images. Also, the coating improves scratch resistance and lens durability.

Further Reading

Micro Four Thirds has been developing rapidly with the regular release of new cameras and lenses. Information on upcoming lenses can be found on the Olympus roadmap and the Panasonic roadmap. Also, did you ever wonder how many shots your mFT camera has already taken? Find out on the Olympus shutter count and the Panasonic shutter count pages.