Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical (IF)

Press Release:
Two years after Tamron launched the SP AF28-75mm f/2.8 XR Di lens as a standard, compact, fast standard zoom lenses, it remains highly popular with advanced amateur and professional photographers alike. Now Tamron, moving with market trends, has unveiled a new design for fast standard zoom lenses used exclusively for digital SLR cameras that covers the easy to use angles of view: the focal length is equivalent to 26-78mm when converted to a 35mm format. In particular, the wide-angle focal length is established at 17mm (26mm equivalent) to obtain a wider angle of view than ordinary standard zoom lenses, while maintaining the remarkably lightweight and compact size of the earlier full frame zoom lens model.

Main features
Lightweight, Compact Fast Standard Zoom Lens, Designed Exclusively for Digital SLR Cameras, with 17mm Wide Angle Coverage
The lens covers virtually the same angle as focal lengths of 26-78mm when converted to a 35mm format. The wide-angle focal length is established at 17mm (26mm equivalent) to obtain a wider angle of view than ordinary standard zoom lenses. Since the lens is designed exclusively for APS-C sized digital cameras, the image circle diameter has been reduced.

Optical System Uses Special Glass, and Is Optimized for Digital SLR Characteristics to Enhance Optical Quality in a Compact Design
The use of XR (Extra Refractive Index) glass optimizes the overall distribution of optical power and also reduces various aberrations to the absolute minimum. In addition, two hybrid aspherical elements maintain imaging performance and help compress the entire optical system. Furthermore, an LD (Low Dispersion) glass element is used to accomplish effective compensation of on-axis and lateral chromatic aberrations.

Minimum Focus Distance - The new lens achieves a minimum focus distance of 27cm over the entire zoom range, one of the best in its class among fast standard zoom lenses with an F/2.8 maximum aperture throughout the entire zoom range used exclusively for digital SLR cameras with APS-C sized image sensors. The maximum magnification ratio of 1:4.5 at the 50mm setting is the top level in its class.

Optical Design Dedicated to Digital SLR Photography This zoom lens uses an optical system designed to confine the changing angles of incidences of light rays reaching the imager within a certain scope over the entire image field by considering the effects of variance due to zooming.

Enhanced Peripheral Illumination - Peripheral light fall-off is minimized when compared with that of conventional lenses for film cameras, so images are uniformly bright from the centre to the periphery.

Outstanding Resolution - Since the lens is designed exclusively for digital SLR photography, it provides high image quality resolution, contrast and flatness of image field.

Internal Surface Coating to Reduce Ghosting and Flare - By employing Internal Surface Coatings (i.e., multiple-layer coatings on cemented surfaces of plural elements) and new multiple-layer coating technology on ordinary elements, ghosting and flare due to the reflections that occur when light enters through the front element and reflections caused by the imagers themselves are reduced to the absolute minimum.

Large Aperture in Lightweight, Compact Design Thanks to New Mechanical Devices - Complicated mechanisms are built into the compact body for excellent portability and ease of use. In addition, a complex triple cam structure where cams zoom and focus within a three-layer lens barrel has been further developed to improve AF focus precision for close-in shots and torque irregularity when zooming in and out. Additionally, the engineering of the lens has been completely overhauled to downsize its parts and to increase their precision and durability.

Zoom Lock Mechanism Incorporated A Zoom Lock prevents unwanted barrel extension when carrying the lens/camera combination.

Flower-Shaped Lens Hood - included as a standard accessory, it provides optimum shading of superfluous light rays that enter from the rectangular frame outside the image field.

New External Design of the New Di II Series - Improvements have been made to the external design by adding a gold-coloured band between the focus and zoom rings to enhance the appearance and make the product stand out as a Di-II lens. The rubber patterns of the zoom rings have also been improved to provide better handling.

Specifications
Maximum Aperture F/2.8
Angle of View 7845-3111 (APS-C size equivalent)
Lens Construction 16 elements in 13 groups
Minimum Focus Distance 0.27m (Over the entire zoom range)
Maximum Mag. Ratio 1:4.5 (at f=50mm MFD 0.27m)
Filter Diameter 67mm
Overall Length 81.7mm *
Maximum Diameter 74.0mm
Weight 434g (General design value)
Diaphragm Blades 7 blades (Circular apertures)
Minimum Aperture F/32
Standard Accessory Flower-shaped Lens Hood
Compatible Mount Nikon AF-D, Canon AF, Konica Minolta AF-D
Availability May 2006
* Values given are for Nikon AF cameras.

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