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Tamron - Lens Dictionary

VC (Vibration Compensation)

The highly evaluated VC (Vibration Compensation) mechanism originally developed by Tamron delivers exceedingly stabilized viewfinder images for remarkable hand-held photography without annoying motion delay. The VC mechanism exhibits its camera-shake compensation performance to the maximum extent at dusk, in dimly-lit indoor situations, or in hand-held shooting at the ultra-telephoto settings.

Di (Digitally Integrated)

Featuring coating optimized for digital SLRs, but still usable on 2436mm sensors (35mm, full or double frame)

Di II

Lenses for DSLRs with APS-C sized sensors only

USD - Ultrasonic Silent Drive

Lens equipped with Tamron's ultrasonic auto-focus drive USD (Ultrasonic Silent Drive) achieves faster focusing making lens perfect for photography of sports, motor racing, and other fast-moving subjects. With advanced motor technology and newly developed software, Tamron's USD delivers precise and noiseless focusing at turbo speed.

Tamron's USD works with the high-frequency ultrasonic vibrations that are produced by a ring called a 'stator'. Energy from the vibrations is used to rotate an attached metallic ring known as the 'rotor'. Piezoelectric ceramic, an element that produces ultrasonic vibrations when voltage of a specific frequency is applied is arranged in a ring formation on the stator. This electrode configuration of piezoelectric ceramic causes two ultrasonic vibrations to occur in the stator.
By effectively combining these two ultrasonic vibrations, it is possible to convert the energy from the vibrations that produced simple motion into energy known as 'deflective traveling waves', which then moves around the circumference (rotation direction) of the ring.
With the USD, the friction between these deflective traveling waves created on the metallic surface of the stator and the surface of the rotor produce force, causing the rotor to rotate. The focusing ring lens, which is linked to the rotor, is thus moved, creating a fast and smooth auto-focus drive.

SP - Super Performance

Tamron's "SP" designation stands for "Super Performance". Tamron's original SP symbol is shown above left. Tamron's current SP symbol is shown to the right of the original symbol. In the past, Tamron's lenses received the SP designation for any of or a combination of the following reasons:

  • Superior sharpness and contrast due to an advanced or unique optical design.
  • Low dispersion element(s) for apochromatic or near apochromatic performance.
  • Internal focusing (compared to similar lenses of the era).
  • Superior macro performance (compared to similar lenses of the era).
  • An exceptional zoom range compared to similar lenses.
  • A larger maximum aperture compared to similar lenses.

Today, many lenses produced by Tamron and other manufactures feature low dispersion elements and internal focusing. It appears that Tamron currently reserves its SP designation for lenses which meet any or a combination of the following criteria:

  • Superior sharpness and contrast due to an advanced or unique optical design.
  • Superior macro performance compared to similar lenses.
  • An exceptional zoom range compared to similar lenses.
  • A larger maximum aperture compared to similar lenses.

Older Tamron SP lenses were simply marked with the letters "SP" somewhere on the lens barrel (usually above the aperture ring), and many SP lenses also had "TAMRON SP" marked on the front element retaining ring and/or on the included built-in or standard accessory lens hood. Today's modern Tamron SP lenses are distinctively marked with a thin gold ring about the top of the lens barrel.

IF - Internal Focus

Tamron's "IF" designation stands for "Internal Focusing". Tamron lenses with an IF desination incorporate internal focusing wherein the length of the lens does not change while the lens is being focused. This is because a group of internal focus elements are moved, in order to acheive focus, rather than moving the frontmost lens elements. Movement of these internal focus elements is very similar to moving the variator and compensator lens groups within a zoom lens, but instead the lens is being focused rather than being zoomed. Some Tamron IF lenses also featured a variable IF cam, much like the variable zoom cams found within zoom lenses, which produced a faster and much more natural focusing collar movement at very close focus distances. This is a useful feature in close-up and macro photography since it allows the photographer to quickly focus the lens while in macro mode. Tamron's older IF lenses were marked with the letters "IF" somewhere on the lens barrel.

XR - Extra Refractive Index

Tamron's "XR" designation stands for "Extra Refractive Index" lens optics. Lenses with XR optics for the frontmost elements are somewhat more compact than similar lenses which use optics with less powerful refractive indices. XR optics allow wide angle lenses, wide angle zooms and wide angle to telephoto zooms to have a somewhat smaller overall diameter. XR optics can potentially allow long telephoto lenses to be shorter in overall length, thus reducing weight.

LD (Low Dispersion)

Extra Refractive Index glass. Tamron's "LD" designation stands for "Low Dispersion". Tamron lenses with a LD desination incorporate one or more very low dispersion elements. Almost always, Tamron used two low dispersion elements to achieve apochromatic performance which was similar to lenses which incorporated a fluorite element. Tamron's older LD lenses were distintively marked with a thin bright green ring around the top of the lens barrel and featured the letters "LD" somewhere on the lens barrel. Tamron has done away with the thin bright green ring for designating its modern lenses which incorporate LD lens elements.

ZL (Zoom Lock)

Tamron's "ZL" designation stands for "Zoom-Lock" mechanism. Many of today's zoom lenses utilize two or more zoom cams and feature large front elements which also move when the lens is zoomed. In some zoom lens designs, it is simply unavoidable for the zoom setting not to creep when the lens is tilted up or down. Tamron neatly solved this problem by incorporating a zoom-lock mechanism which locks the zoom setting in place.

source: Tamron Lenses, Wikipedia, Adaptall