The Tamron SP AF 17-50mm F2.8 XR Di ll LD Aspherical (IF) Pentax Fit lens is a lightweight, compact, fast standard zoom lens, designed exclusively for use with digital SLR cameras (APS-C Size). The wide-angle focal length of 17mm (equivalent to 26mm) obtains a wider angle of view than the standard zoom lens without any increase in size or weight. The fast f/2.8 aperture gives a natural out-of-focus effect which is great for portraits, whilst the minimum focusing distance of 27cm over the entire zoom range gives a maximum magnification ratio of 1:4.5 at 50mm. The Tamron 17-50mm f2.8 XR Di-II LD ASP IF lens optimises the overall distribution of optical power via the use of XR (Extra Refractive Index) glass. A Low Dispersion glass element is used to effectively compensate on-axis and lateral chromatic aberrations.
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 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.
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.
The technical jargon
Lenses are designed for exclusive use on digital cameras with smaller-size imagers (also known as APS-C sensors). These lenses are not designed for conventional cameras and digital cameras with image sensors larger than 24mm x 16mm.
|Focal length (wide)||17|
|Focal length (tele)||50|
|Max aperture (wide)||2.8|
|Sensor format||APS-C size|
|Filter thread (mm)||67|
|Minimum focus distance||0.27m|