AF18-200mm F/3.5-6.3 XR Di II LD Aspherical (IF)
Model A014

A high-power zoom lens is designed for exclusive use with digital SLR cameras using smaller-size imagers

This lens inherits the product concept of the extremely popular AF28-300mm F/3.5-6.3 XR Di zoom lens. The wide to ultra-tele focal range of this lens allows digital SLR camera owners* to enjoy digital photography with the same comfort and convenience previously afforded to film users.

FEATURE SUMMARY

Dedicated for digital SLR cameras
By incorporating an optical design for exclusive use with digital SLR cameras with smaller-size imagers, this high-power zoom lens provides the same focal length, when converted to a 35mm format, equivalent to Tamron's 28-300mm. Therefore, you can meet virtually every photographic opportunity with this single zoom lens without changing lenses. When paired with the ultra-wideangle SP AF11-18mm zoom, you can thoroughly enjoy digital SLR photography with a combined equivalent focal length coverage of 17-300mm.

Optical system uses special glass and is optimised for digital SLR characteristics in order to enhance optical quality in a compact design
The new AF18-200mm high power zoom lens from Tamron features an entirely new optical design using XR (Extra Refractive Index) glass in an innovative way in order to optimize the overall distribution of optical power throughout the entire zoom range. This design reduces various aberrations to the absolute minimum and achieves remarkable downsizing at the same time. In addition, three hybrid aspherical lens elements and two LD (Low Dispersion) glass elements are used to accomplish effective compensation of on-axis and lateral chromatic aberrations, a critical factor to enhance the optical quality in digital photography. As a result, this lens is truly multi-purpose but still provides outstanding image quality.

Optical design dedicated to digital SLR photography by optimising the angles of incidences of light rays reaching the image sensor
The zoom lens uses a new 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 from the center to the periphery, by considering the effects of variances due to zooming.

Enhanced peripheral illumination
Peripheral light fall-off is minimised when compared with that of conventional lenses for film cameras so that 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 in terms of resolution, contrast and flatness of image field.

Internal surface coating to reduce ghosting and flare
Ghosting and flare caused by aberrations are annoying factors in digital SLR photography, so Tamron has adopted various countermeasures against the problem including the employment of “Internal Surface Coatings” (i.e., multiple-layer coatings on cemented surfaces of plural elements) and new multiple-layer coating technology on ordinary elements in order to minimise reflections that occur when light enters through the front element and to reduce image degrading effects caused by the imagers themselves.

Revolutionary minimum focus distance – 0.45m (17.7") for 1:3.7* macro capability
It is an important condition for a multi-purpose zoom lens to provide the capability of getting close to the subject. The new 18-200mm zoom lens realises an MFD (Minimum Focus Distance) of 0.45m (17.7") through the employment of a new optical/mechanical design configuration. Since the maximum magnification ratio at 200mm is 1:3.7*, you can enjoy close-up photography easily and conveniently.

* The Maximum Magnification Ratio of this lens is 1:3.7 while the Maximum Magnification Ratio of the AF28-300mm (Model A061) is 1:2.9. However, the 18-200mm can fill the frame with almost the same scope as the A061 does when shooting with a 35mm SLR camera, since the new lens is exclusively designed for digital SLR cameras with smaller-size imagers. The Maximum Magnification Ratio of 1:3.7 is equivalent to 1:2.8 when converted to 35mm film format.

High power, yet compact and lightweight thanks to newly developed mechanisms
New and complex mechanisms are hidden in this lens' compact construction. Several engineering innovations were required to downsize the design, produce high-precision parts and increase durability, imbuing this multi-purpose zoom lens with excellent portability and ease of use.

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.

New external design on the Di-II series conveys "high-performance, high-precision" image
Improvements have been made to the external design by adding a gold-colored band between the focus and zoom rings to enhance the appearance and make it stand out as a Di-II lens. The rubber patterns of the zoom and focus control rings have been improved at the same time 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.

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.

© Copyright 2001–2009 Tamron Co Ltd