Tamron Announces the AF18-270MM Di II VC Ultra High Power Zoom Lens
MAIN FEATURES
1.World's first and greatest zoom ratio of 15X, covering 28-419mm 35mm-equivalent angle of view
Going back to the basic concept of "one lens covering everything from wide angle to telephoto," engineers at Tamron took up the difficult task of expanding the zoom range of Tamron's high power zoom lenses even further. Their unstinting efforts to extend the telephoto end beyond previous limits while retaining the wide-angle end at 18mm has borne fruit as an ultra high power zoom lens that is exclusively designed for DSLR cameras and boasts the greatest zoom range of 15X for the first time in the world.
2. Tamron's original VC mechanism for effective shake-free hand-held photography
Tamron's proprietary VC (Vibration Compensation) mechanism was built in the AF28-300mm F/3.5-6.3 Di VC (Model A20) for the first time. It demonstrated its powerful compensation effect employing a tri-axial system that is designed to let three coils drive a compensator lens electromagnetically via three steel balls. Since the compensator lens is supported on rolling steel balls with very low friction, follow-up performance is also enhanced, resulting in stabilized viewfinder images. Since the mechanism is designed to allow parallel shifting of the compensator lens solely by means of electrical control, the mechanical construction is simpler and more compact, so the lens can be kept as small and light as possible.
3. Designing a high power, compact zoom lens with VC mechanism: Optical design optimization meets optimum power distribution
In developing the long-range zoom lens, Tamron's optical designers pursued the optimum distribution of power within the overall optical system based on the optical design know-how Tamron accumulated over 16 years since the introduction of the first compact AF28-200mm in 1992. The resulting optical system uses two LD (Low Dispersion) glass elements and three aspherical elements in order to effectively compensate for various aberrations including astigmatism, yet this design allows the first optical group to be small enough in diameter to realize the overall goal of a compact lens that incorporates a handheld-shake compensation mechanism.
Note: In order to realize the high zoom ratio of 15X, the optical system does not use any XR (extra dispersion glass) element. Instead, compactness is achieved through optimization of the power distribution within the whole optical system.
4. Minimum focusing distance of 19.3" over the entire zoom range for the max. mag. ratio of 1:3.5
The AF18-270mm Di II VC allows close focusing down to 0.49m (19.3 inches) from the subject over the entire zoom range even though it incorporates the VC mechanism. The maximum magnification ratio of 1:3.5 at its 270mm telephoto end is the top class capability among high power zoom lenses exclusively designed for digital SLR cameras.
5. Optical system optimized for digital SLR cameras by taking incident rays of light reaching the image sensor into consideration
In order to effectively compensate for changes in aberrations due to zooming, the zoom lens employs an innovative optical system that is designed to converge the angles of rays of light entering from the center to the periphery of the lens. The light rays thus reach the image sensor within a defined circle that assures high imaging performance and reduces light falloff.
6. High resolution performance
As a lens exclusively designed for digital SLR cameras, this zoom lens delivers high resolution and contrast performance for outstanding image quality with sufficient flatness of the field under an extremely wide range of photographic conditions.
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