Super Performance series
Performance takes priority for superb image quality
This line of ultra-high-performance lenses is designed and manufactured to the exacting specifications demanded by professionals and others who require the highest possible image quality. The foremost priority is achieving superior performance parameters – high design standards take priority over cost constraints. As a result, Tamron SP lenses feature innovative designs that have established an enviable reputation for excellence amongst demanding photographers.
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.
Complicated mechanisms are built into this compact profile 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-up shots and control of torque when zooming. A comprehensive engineering overhaul has downsized its parts and increased their precision and durability, making the body lightweight and compact with a filter diameter of 67mm, overall length of 81.7mm (3.2”)*, and weight of 434g (15.3oz.)*.
* Values given are for Nikon AF cameras.
IF – Internal Focusing
Focusing elements inside the optical design make for better handling
In many lenses, the front elements move back and forth to alter the focus distance. With an internal focusing (IF) mechanism, the focusing elements are inside the optical design. Because the front lens elements remain static, the lens’ actual length does not change. This provides several benefits both to the image and during photography:
- The barrel is not subject to stray light entering from external helicoids that can adversely affect image quality
- A non-rotating front filter thread makes it easier to use filters such as graduated filters and polarisers
- A flower-shaped lens hood will remain in the correct position to most effectively shield the lens from stray light
- Better balance and more predictable handling because the lens length does not change during focusing
- Generally, a much closer minimum focusing distance 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.
Integrated focus cam optimises internal focusing
Tamron’s Integrated Focus Cam is a precision mechanical component that optimises the co-ordinated movement of the Internal Focusing (IF) system with the Multiple Cam Zoom Mechanism. This ingenious mechanism ensures accurate and seamless positioning of all the internal elements within the lens and coordinates them with the external zoom and focus controls.
Revolutionary minimum focus distance of 27cm over the entire zoom range provides a 1:4.5 macro capability
The lens achieves a minimum focus distance of 27 cm (10.6”) over the entire zoom range, the best in its class. The maximum magnification ratio of 1:4.5  at the 50mm setting is the top level in its class.
ZL – Zoom-lock mechanism
Useful when carrying the lens/camera over the shoulder
Another original Tamron mechanical engineering concept is the zoom-lock mechanism, which prevents the weight of the lens barrel from extending the lens when carried on the camera pointing downward. This eliminates the danger of accidentally knocking the lens while walking around and enhances responsiveness in the field. Simply zoom the lens out to its widest focal length and use the sliding zoom-lock switch to lock the barrel in place.
Flower-shaped hood is supplied with the lens to shield stray light
Included as a standard accessory, the flower-shaped hood matches the rectangular shape of the image sensor to most effectively block the interference of superfluous light rays entering from outside the borders of the image area, helping to ensure sharp, clear, flare-free images with crisp detail in the shadow areas.
 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.
 As of 15th December 2005. Based upon Tamron research of lenses in the same class. As 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.