The Tamron 70-200mm f2.8 SP Di VC USD Lens Nikon Fit is a high-speed telephoto zoom lens with an Ultrasonic Silent Drive that achieves leading-edge image quality while boasting the most compact design in its class. The USD (Ultrasonic Silent Drive) delivers speedy AF (Autofocus) and the moisture-resistant construction helps keep the rain out. The design features 23 elements on 17 groups, including four Low Dispersion glass elements for minimising chromatic aberration. Vibration Compensation provides a stable viewfinder image with excellent tracking performance. The ’SP’ in the title indicates it is one of Tamron’s top-line ‘Special Performance’ lenses and ‘Di’ stands for Digitally Integrated which means this lens can be used on cameras with full frame and APS-C sized sensors.
Di (Digitally Integrated)
Is the designation Tamron puts on lenses featuring optical systems designed to meet the performance characteristics of digital SLR cameras as well as film cameras. These lenses may be used on cameras with full format (FF) or APS-C sensors (with a crop factor relative to the camera).
SP (Super Performance)
Professional class lens; currently the best lenses made by Tamron for the consumer market.
Tamron’s USD works with high-frequency ultrasonic vibrations which are produced by a ring called a ‘stator’. Energy from the vibrations is used to rotate an attached metallic ring known as a ‘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 of the lens, which is linked to the rotor, is thus moved, creating a fast and smooth auto-focus drive.
VC Vibration Compensation
The VC (vibration Compensation) mechanism is a Tamron development which ensures an effective compensation for camera vibrations. Especially hand-held, low-light and tele photography is susceptible for camera shake and consequent blurred results, due to the required longer shutter speeds. Under these photographic conditions the VC mechanism can unfold to its full efficiency.