SP AF17-50mm F/2.8 XR Di II LD Aspherical [IF]
Model A016 and A016P for Pentax

This lightweight, compact, fast standard zoom lens featuring a true wide angle is designed exclusively for digital SLR cameras

Expanding the product concept of the popular SP AF28-75mm F/2.8 XR Di LD Aspherical IF zoom lens – launched as the standard for lightweight, compact, fast standard zooms – Tamron's next design, exclusively for digital SLR cameras, covers all the most popular 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.

In addition, portrait shots are made beautiful with the natural out-of-focus effect characteristic provided by the fast f/2.8 aperture. Additionally, a broader photographic expression through the use of faster shutter speeds as a result of the maximum aperture offers enhanced photographic pleasure. The minimum focus distance of 0.27m over the entire zoom range achieves a maximum magnification ratio of 1:4.5 at 50mm. The lens boasts one of the best close-up shooting performances in the class of fast standard zoom lenses designed exclusively for digital cameras and featuring an F/2.8 maximum aperture throughout the entire zoom range, to ensure stress-free photographic shots at all focal lengths and distances.

MAIN FEATURES

Lightweight, compact fast standard zoom designed exclusively for digital SLRs, with 17mm wide-angle coverage
Exclusive design for digital SLR cameras achieves a fast standard zoom lens that covers virtually the same angles 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, while maintaining the remarkably lightweight and compact size of the earlier full frame zoom lens model. Since the lens is designed exclusively for APS-C sized digital cameras, the image circle diameter has been reduced. Moreover, careful adjustments to the design have achieved a lightweight, compact body with a filter diameter of 67mm, overall length of 81.7mm (3.2”)*, and weight of 434g (15.3oz.)* (General design value).

* Values given are for Nikon AF cameras.

Optical system uses special glass, and is optimised for digital SLR characteristics to enhance optical quality in a compact design
The use of XR (Extra Refractive Index) glass in an innovative way optimizes the overall distribution of optical power, and also reduces various aberrations to the absolute minimum while achieving remarkable compactness. In addition, suitable positioning of two hybrid aspherical elements serves to maintain imaging performance and to shorten and 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, a critical factor for enhancing optical quality in digital photography, in order to achieve outstanding optical performance over the entire zoom range.

Revolutionary minimum focus distance of 27cm (10.6”) over the entire zoom range provides a 1:4.5 macro capability
The new lens achieves a minimum focus distance of 27 cm (10.6”) over the entire zoom range, 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 [1] at the 50mm setting is the top level in its class.

[1] As of 15th December 2005. Based upon Tamron research of lenses in the same class.
[2] Since APS-C sized image sensors are smaller than 35mm film, the 17-50mm can fill the frame with almost the same scope as a lens with a maximum magnification ratio of 1:3.0 on a 35mm SLR camera.

Optical design dedicated to digital SLRs optimises the angle of incidence of light rays reaching the image sensor
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 reduces 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 design
Complicated mechanisms are built into a compact body for excellent portability and ease of use. A complex triple cam structure, where cams zoom and focus within a three-layer lens barrel, improves AF focus precision for close-in shots and torque irregularity when zooming. Additionally, the engineering of the lens has been completely overhauled to downsize its parts and to increase their precision and durability, thereby accommodating the lens' complex structure.

Zoom Lock mechanism
The Zoom Lock prevents unwanted barrel extension when carrying the lens/camera combination.

Flower-shaped lens hood
A glare-reducing flower-shaped lens hood is included as a standard accessory. The special hood provides optimum shading of superfluous light rays that enter from the rectangular frame outside the image field.

External design of the Di-II series conveys 'high-performance, high- precision' image
Cosmetic improvements, including a gold-colored band between the focus and zoom rings, enhance the appearance and make the product stand out as a Di-II lens. Also, the black coating over the entire lens barrel creates a high-quality, sophisticated look. The rubber patterns of the zoom rings have also been improved to complement the digital camera design style and to provide better handling.

SPECIFICATIONS

NOMENCLATURE

Digitally Integrated Design for DSLRs with small sensors

Di II lenses are designed for exclusive use on digital SLR cameras with APS-C-format image sensors. All Di II lenses are optimised to meet the performance characteristics of DSLRs, providing maximal resolution concentrated within the image field and assuring that light rays at the edges of the frame reach the sensor at favourable angles, thereby minimising peripheral light falloff.

In addition, all Di II lenses incorporate effective measures to increase light transmission and eliminate ghosting and flare, which are particularly noticeable with digital cameras. Tamron’s advanced multi-coatings are applied not only to external and internal lens surfaces, but also to surfaces in between cemented lens elements. Finally, Di II lenses are offered in a wide array that includes the focal length ranges most desired by DSLR shooters.

Super Performance series

Tamron SP (Super Performance) series is a line of ultra-high-performance lenses designed and manufactured to the exacting specifications demanded by professionals and others who require the highest possible image quality. In creating SP lenses Tamron’s optical designers put their foremost priority on achieving superior performance parameters – they are all designed to a higher standard with little regard for cost constraints. As a result, Tamron lenses bearing the SP designation feature impressive and innovative designs that have established an enviable reputation for excellence among those knowledgeable photographers that demand the very best.

Extra Refractive Index

XR (Extra Refractive Index) glass can bend light rays at steeper angles, thereby decreasing the physical length of the lens while enhancing imaging performance by minimising optical aberrations. This has allowed Tamron to develop a line of shorter, smaller-diameter, lighter lenses without sacrificing lens speed, actually upgrading image quality compared to older designs.

XR glass is costlier than conventional glass but it yields enhanced optical power distribution, making possible many of the outstanding and innovative lens designs that bear the XR designation.

Low Dispersion

Chromatic aberration occurs when a lens element refracts different wavelengths of a ray of light – its rainbow colours – at very slightly different angles. This results in the 'colour fringing' that reduces the sharpness of an image. LD elements are made from special glass materials with extremely low dispersion indices (i.e. the refraction of a ray of light into rainbow colours is extremely narrow). Thus they effectively compensate for chromatic aberration at the centre of the field (on axis), a particular problem at long focal lengths (the telephoto end of the zoom range), and for lateral chromatic aberration (toward the edges of the field) that often occurs at short (wideangle) focal lengths. Although costly, LD glass materials result in clear, vivid image quality.

Aspherical

Tamron uses several hybrid aspherical lens elements in its lenses bearing the Aspherical designation. These innovative optics achieve the ultimate in image quality while producing lenses that offer remarkable zoom ranges in extraordinarily compact packages. These cutting-edge advances have advanced the state of optical design by virtually eliminating spherical aberration and image distortion from Tamron's high-power-zoom series.

As one hybrid aspherical lens element can take the place of multiple elements without compromising performance, remarkably compact long-range lenses can now deliver a uniformly high level of image quality across all focal lengths and apertures.

Internal Focusing

Tamron's internal focusing (IF) mechanism provides numerous practical benefits to photographers including:

• a non-rotating front filter ring that facilitates the positioning of polarising and graduated filters
• more predictable handling because the lens length does not change during focusing
• a much closer minimum focusing distance (MFD) throughout the zoom range
• improved optical performance by minimising loss of illumination at the corners of the image field (vignetting)
• suppression of other aberrations that become more troublesome at different focusing positions.

Specifications, design, product name and standard accessories may differ by country or area. While every effort has been made to ensure accuracy, these matters are subject to change by the manufacturer without notice or obligation.

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