Tuesday, August 10, 2010
Tamron SP 70-300mm
Features include image stabilization and autofocus driveProduct Features
New optical system optimized for digital cameras achieves top resolution in the 70-300mm class with specialized glass elements including an XLD (Extra Low Dispersion) lens - This lens’ advanced optical design employs a sophisticated XLD (Extra Low Dispersion) lens element made from specialized high-grade glass that has lower dispersive properties than standard LD lenses (where refraction causes the dispersion of white light into spectral hues). The dispersive properties of the XLD lens are at a level similar to fluorite, and in combination with LD elements make for an optimal optical design that delivers best in class resolution with advanced axial chromatic and magnification aberration correction - major inhibitors of image quality enhancement. The result is a lens that delivers sharp contrast and better descriptive performance throughout the entire zoom range.
• Fast focusing USD (Ultrasonic Silent Drive), the ultrasonic autofocus drive - The lens is equipped with Tamron’s first-ever ultrasonic auto-focus drive USD (Ultrasonic Silent Drive). It achieves faster focusing making this telephoto 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.
USD (Ultrasonic Silent Drive)
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 to produce 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.
Equipped with Tamron’s VC (Vibration Compensation) image stabilization
The SP 70-300mm Di VC USD employs Tamron’s esteemed image stabilization mechanism–VC (Vibration Compensation) seen in both the AF18-270mm Di II VC (Model B003) and SP AF17-50mm F/2.8 XR Di II VC (Model B005). With VC, the photographer has the freedom to shoot at a shutter speed that is an extra four stops slower without having to worry about blurring. This makes capturing handheld, evening, night, and interior shots much easier.
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