Lens Buying Guide – Lens Specifications – What Does it All Mean?

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Lens Specifications… What does it all mean?

Manufacturers incorporate standard terminology when describing basic characteristics of their lenses, including lens type (wide angle, zoom, etc.), focal length (50mm, 100mm, etc.) and f-stops (f/2.8, f/8, etc.). But what do all the other acronyms stand for?

Some manufacturers give their lenses brand names, but usually you will find that they also list the camera’s specifications in acronyms. Too often these acronyms are manufacturer-specific; in addition, some of the features are exclusive to each manufacturer.

Here is a handy guide to the acronyms that each manufacturers use, their definitions and their functions.

AcronymDefinitionFunction
AFAutoFocusThe camera lens focuses the image of a selected part of the picture or subject. Most camera bodies allow you to set exact focus spots for you lens to focus on.
EDExtra-low Dispersion GlassOffers superior sharpness and colour correction by minimizing chromatic aberration. ED glass has all the benefits of calcium fluorite-based glass without the fragility. Nikon has developed several types of ED glass suitable for the various lenses they produce.
SICSuper Integrated CoatingMulti-layer lens coating that helps reduce ghost and flare to a negligible level enhancing the performance of its optical lens elements. This coating minimizes reflections in the wider wavelength range and superior colour balance and reproduction.
NNano Crystal CoatAnti-reflective coating that originated in the development of NSR series (Nikon Step and Repeat) semiconductor manufacturing devices. Virtually eliminates internal lens element reflections across a wide range of wavelengths, and is particularly effective in reducing ghost and flare peculiar to ultra-wide angle lenses. Nano Crystal Coat employs multiple layers of extra-low refractive index coating, which features ultra fine crystallized particles of nano size (one nanometer equals one millionth of a mm).
ASFAspherical Lens ElementsAspherical lenses virtually eliminate the problem of coma and other types of lens aberration — even when used at the widest aperture. They are particularly useful in correcting the distortion in wide angle lenses. In addition, use of aspherical lenses contributes to a lighter and smaller lens design. Nikon employs three types of aspherical lens elements. Precision-ground aspherical lens elements are the finest expression of lenscrafting art, demanding extremely rigorous production standards.

Hybrid lenses are made of a special plastic moulded onto optical glass. Moulded glass aspherical lenses are manufactured by moulding a unique type of optical glass using a special metal die technique.

CRCClose-Range Correction SystemProvides superior picture quality at close focusing distances and increases the focusing range. With CRC, the lens elements are configured in a “floating element” design wherein each lens group moves independently to achieve focusing. This ensures superior lens performance even when shooting at close distances. The CRC system is used in fisheye, wide angle, Micro, and selected medium telephoto Nikkors
IFInternal FocusingLenses that can focus without changing its size. All internal optical movement is limited to the interior of the non-extending lens barrel. This allows for a more compact, lightweight construction as well as a closer focusing distance. In addition, a smaller and lighter focusing lens group is employed to ensure faster focusing. The IF system is featured in most Nikkor telephoto and selected Nikkor zoom lenses.
RFRear FocusingLens elements are divided into specific lens groups, with only the rear lens group moving for focusing. This makes auto-focusing operation smoother and faster.
DCAF DC-Nikkor LensAF DC-Nikkors feature exclusive Nikon Defocus-image Control technology. This allows photographers to control the degree of spherical aberration in the foreground or background by rotating the lens’ DC ring. This will create a rounded out-of-focus blur that is ideal for portrait photography.
DDistance InformationD-type and G-type Nikkors relay subject-to-camera distance information to AF Nikon camera bodies. This then makes possible advances like 3D Matrix Metering and 3D Multi-Sensor Balanced Fill-Flash.
SWMSilent Wave MotorSWM which converts “traveling waves” into rotational energy to focus the optics. This enables high-speed auto-focusing that’s extremely accurate and super quiet.
M/AM/A ModeAllows switching from auto-focus to manual operation with virtually no time lag — even during AF servo operation and regardless of AF mode in use.
VRVibration ReductionMinimizes image blur caused by camera shake, and offers the equivalent of shooting at a shutter speed three stops (eight times) faster.* It allows handheld shooting at dusk, at night, and even in poorly lit interiors. The lens’ VR system also detects automatically when the photographer pans — no special mode is required.
DXDX NikkorCompact and lightweight DX Nikkor lenses featuring a smaller image circle are specially designed and optimized for Nikon D2-series, D1-series, D200, D80, D100, D70s/D70 and D50 digital SLR cameras. These are ideal options for landscape photographers and others who need to shoot expansive scenes with Nikon DX-Format digital SLRs.

See all Nikon Lenses »

AcronymDefinitionFunction
AFAutoFocusThe camera lens focuses the image of a selected part of the picture or subject. Most camera bodies allow you to set exact focus spots for you lens to focus on.
ISImage StabilizerMakes hand held photography possible in more low-light situations. IS lenses have a special of lens elements that automatically shifts its position, thereby compensating for the shake and stabilizing the image. This compensation effectively adds up to three shutter speed steps to your hand held shooting capability depending on the IS lens. Canon’s IS lenses are perfect for low light, or situations where a tripod is not convenient.
USMUltrasonic MotorThe Ultrasonic Motor spins the lens motor with ultrasonic oscillation energy. Instead of a large, noisy drive-train system, electronic vibrations created by piezoelectric ceramic elements power the mechanical action of the lens, providing constant torque, with virtually instantaneous stops and starts. USM lenses are both faster and quieter than conventional motor driven autofocus systems, and draw minimal power from the camera, draining very little battery power.

Canon makes two types of Ultrasonic lenses. Ring-type USM-equipped lenses, found in large aperture and super-telephoto designs, allow manual focusing without switching out of the auto mode. Micro USM designs bring the performance benefits of Canon’s USM technology to a wide assortment of affordable EF Lenses.

DODiffractive OpticsHigher performance and more compact than those with traditional refractive designs. Canon’s multilayer diffractive elements work together with conventional glass optics to cancel the effects of dispersion and minimize or eliminate chromatic aberration.

In addition to chromatic aberration correction, this technology also results in smaller lenses, with no compromise in quality. Canon has also developed a new Triple-layer type DO lens using a new three layer diffractive grating resulting in high image quality with high levels of resolution and contrast that rival the L-series lenses.

LL Series LensProfessional line of Canon lenses identifiable by a bold red ring around the outer barrel, these lenses are distinctive in their performance through use of optical technologies like Ultralow Dispersion UD-glass, Fluorite and Aspherical elements and Super Spectra Coating.

Fluorite / UD Elements

Ultra-low Dispersion glass to minimize colour fringing or chromatic aberration. The design of UD glass provides outstanding contrast and sharpness and minimizes the splitting of colors as they pass through the elements, resulting in cleaner color throughout the image. Even more effective at suppressing chromatic aberration are Fluorite elements used in high-end supertelephoto lenses. A single Fluorite element has the corrective power of two UD-glass elements, giving these L-series lenses their spectacular performance and relatively compact design.

Aspherical Elements

Aspherical optics also help to correct curvilinear distortion as one would find in ultra wide-angle lenses. They have an extremely precise variable curvature of one or both sides allowing for more compact and lighter lens designs.

EFEF MountFully electronic mount system that has none of the shock, operational noise, abrasion, play, lubrication requirements, slow response, diminished precision caused by lever operation, or design restrictions related to linkage mechanisms used to transfer data. A lens operation self-test system, using the lens’ built-in microcomputer, can even warn of malfunctions through the camera’s LCD readout to help ensure high reliability. The EF mount allows for high-speed focus, precise aperture control and preview, automatic compensation with lens extenders.
EF-SEF-S MountDesigned for Canon EOS digital cameras with smaller-than-full size APS-C sensors (with a 1.6x conversion factor). The “S” in EF-S stands for “short back focus”, the rear element of the lens is closer to the APS-C sized sensor than the EF 35mm SLR lenses. This enhances the ability of the lens to produce wide and ultra wide angles. These lenses can not be used with full frame digital SLR cameras.
TS-ETilt Shift LensTS-E lenses are capable of tilt and shift movements, which greatly expand picture-taking possibilities. Tilt movements alter the angle of the plane of focus between the lens and film plane, making broad depth-of-field possible even at large apertures or vice versa; shift movements move the lens’ optical axis in parallel, allowing the photographer to change, or correct the perspective of their photograph at almost any angle.

See all Canon Lenses » 

AcronymDefinitionFunction
AFAutoFocusThe camera lens focuses the image of a selected part of the picture or subject. Most camera bodies allow you to set exact focus spots for you lens to focus on.
SPSuper Performance LensOffers superior sharpness and colour correction by minimizing chromatic aberration. ED glass has all the benefits of calcium fluorite-based glass without the fragility.
DIILenses for Digital SLRs onlyDi-II inherits all of the optical benefits of the Di design. Di-II lenses are made for exclusive use on digital cameras with image sensors 24mm x 16mm and smaller and are not intended for use on full-frame D-SLRs or film cameras.
IFInternal FocusingLenses that can focus without changing its size. All internal optical movement is limited to the interior of the non-extending lens barrel. This allows for a more compact, lightweight construction as well as a closer focusing distance. In addition, a smaller and lighter focusing lens group is employed to ensure faster focusing.
ASLAsphericalOffers advantages in compensating for spherical aberrations and distortion for higher image quality as well as in making the lens compact and lightweight by reducing the number of lens elements in the optical system.
LDLow DispersionRealizes high image quality by minimizing sharpness fall off due to chromatic aberration inherent in close focusing at the telephoto end in lenses of conventional optical design
ADAnomalous DispersionSpecial optical glass material that delivers a remarkably large partial dispersion ratio relative to a specific different wavelength zone. Effective compensation of on-axis chromatic aberration for telephoto lenses, or lateral chromatic aberrations often associated with conventional wide angle lenses.
XRExtra Refractive Index GlassGlass having a high refractive index that provides remarkable advantages in making the overall length of the optical system shorter thereby making the lens compact

See all Tamron Lenses »

AcronymDefinitionFunction
ASPAspherical lensesThe aspherical lens complex allows freedom of design, improved performance, a reduced number of component lenses and a compact size. This lens provides high optical performance while maintaining a compact size. For example, the 12-24 mm F4.5-5.6 EX DG ASPHERICAL lens widens the range of wide-angle lenses, and it provides distortion-free images with image reproduction performance equivalent to that of a single focal length lens. Aspherical lenses allow the production of high-quality images from compact, lightweight telephoto zoom lenses.
APOAPO LensIn order to attain the highest quality images, the APO lens has been made using special low-dispersion (SLD) glass and is designed to minimize color aberration. SIGMA’s APO zoom lenses minimize color aberration. As the refractive index of glass depends on the wavelength of light, color aberration occurs when different colors form images at different points. This problem often occurs with telephoto lenses, but the Special Low-Dispersion (SLD) glass and Extraordinary Low Dispersion (ELD) used in SIGMA’s APO lenses helps to compensate for color aberration, thereby allowing them to produce of sharp images.
OSOS (Optical Stabilizer) FunctionThis function utilizes a built-in mechanism that compensates for camera shake. It dramatically expands photographic possibilities by alleviating camera movement when shooting by hand held camera. Developed with Sigma’s own technology, the OS (Optical Stabilizer) function uses two sensors inside the lens to detect both vertical and horizontal movement of the camera. This function, which works by moving an optical image stabilizing lens group, to effectively compensate for camera shake, helps to set our lenses apart from the rest. To handle all types of shooting conditions, the system has two optical stabilizer modes. Mode 1 determines camera shake in vertical and horizontal panning and compensates for image blurring. It is therefore effective for taking general photography or for shooting landscapes and other static subjects. Mode 2 detects vertical camera shake and compensates for blurring. It is effective for panning the camera to photograph moving subjects such as motor sports.
CONV.APO Teleconverter EXThis lens can be used with the APO Teleconverter EX. It can increase the focal length and will interface with the camera’s AE (automatic exposure) function.
EXEX LensThe exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance.
HSMHyper-Sonic MotorThis lens uses a motor driven by ultrasonic waves to provide a quiet, highspeed AF.
IFInner FocusTo ensure stability in focusing, this lens moves the inner lens group or groups without changing the lens’ physical length.
RFRear FocusThis lens is equipped with a system that moves the rear lens group for highspeed , silent focusing. Conventional focusing has normally been performed by moving either all lens groups as a fixed unit or only the first lens group. AF cameras are now widely used, even for close-up photography. Consequently, demand has arisen for a focusing system that will keep the length of the lens unchanged while showing little fluctuation of aberration. In response to this demand, SIGMA has developed a new inner focus system that moves two lens groups inside the telephoto and telephoto MACRO lenses. This system has floating elements that substantially improve the close-up capability of the lens. The super wide angle lens having a large front-lens uses a rear focusing system to move the rear-lens apparatus and enhance the floating effect, and the18-125 mm F3.5- 5.6 DC lens uses an inner focusing system to move the secondary lens apparatus. SIGMA has also succeeded in attaining a minimum shooting distance of 19.7 inches/0.5 m throughout the entire zoom range of this lens. The rear focus system ensures high-speed focusing with the APO 135-400 mm F4.5-5.6 DG and APO 170-500 mm F5-6.3 DG telephoto zoom lenses.
DGDG Lens for DigitalThe most suitable lenses for 35mm film single-lens reflex cameras, as well as for digital SLR cameras. Sigma’s development of the DG (Digital) range of lenses has concentrated on the correction of distortion and aberrations. Magnification of chromatic aberration is particularly conspicuous with digital cameras. The optical designs and cutting-edge technology incorporated by Sigma eliminate flare and ghosting from te image sensor and create excellent color balance. Vignetting is minimized whilst marginal illumination is ensured. These high performance lenses are equally suited for digital and analogue cameras.
DCDC Lens for DigitalThese are special lenses designed so that the image circle matches the smaller size of the image sensor of most digital SLR cameras. Their specialized design gives these lenses the ideal properties for digital cameras, the compact and lightweight construction is an added bonus!
Floating SystemThe floating system is used to control the focus. This system moves the different lens groups in the optical system to different positions, thereby minimizing the telescoping distance and the fluctuation of aberration at different shooting distances. This system is particularly effective for macro lenses (which encompass a wide range of shooting distances) and wide angle lenses (for Single-Lens Reflex cameras) whose lens composition is asymmetric. SIGMA uses the floating system for the MACRO 50 mm F2.8EX DG lens and the large-aperture wide-angle 28 mm F1.8 EX DG ASPHERICAL MACRO lenses.
DFDF (Dual Focus) SystemThe DF (Dual Focus) system disengages the linkage between the internal focusing mechanism and outer focusing ring when the focusing ring is moved to the AF position. This system provides easy and precise handling of the lens, since the focusing ring does not rotate during autofocusing. The wide focusing ring also enables easy and accurate manual focusing.
Zoom MacroAlthough telephoto zoom lenses can be used closer to the object than single-focal length telephoto lenses, there is still a minimum shooting distance. SIGMA has made this minimum distance smaller and developed the zoom MACRO lens for taking close-up photographs of the same quality as those taken with a regular MACRO lens, while maintaining the performance specific to an APO lens. Rather than carrying around the cumbersome accessories required for close-up work, the photographer can now take photographs at a magnification of 1:2 (one half life size) using a telephoto lens, by quickly shifting from the normal setting to the full macro setting.

See all Sigma Lenses »

 

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Woodrow Walden is a Toronto-based photographer and the Social Media Community Specialist for Vistek.