Lightweight. Fast. Super Performance
This 17-50mm is an extremely high-quality standard zoom with a high luminosity of 2.8 over the entire focal length range. It belongs to the Super performance (SP) class of Tamron lenses distinguished by ultra high optical and mechanical quality. The high luminosity that this lens offers is ideal for low-light conditions and professional image composition. The result is images with smooth, even bokeh (background blur), where the subject is virtually released from the background. Apart from the unlimited possibilities that this lens has to offer, it is the quality of your images that stand in the focus.
The world's shortest minimum focus distance of only 27cm was achieved, by using 3 XR glass elements (Extra Refractive) in the front group coupled with a new mechanical design, whilst at the same time keeping the construction compact. The maximum magnification ratio of 1:4.5 and a weight of mere 430g are also a worldwide top*. Image defects are kept at an absolute minimum through the application of aspherical elements and LD (Low dispersion) glass as well as a special coating of internal glass surfaces (Internal Surface Coating). The result is high-quality extremely sharp and excellent images.
The optical design of this lens uses a high-performance XLD (Extra Low Dispersion) element, which is manufactured out of a special glass with an extremely low refractive index. The refractive index describes the ability of the lens to split a light beam into its spectral colours. The dispersive properties are even lower than standard LD lenses and are at a level similar to fluorite. The XLD lens in combination with the LD element delivers the highest contrast and brilliance. This effectively prevents the problem of chromatic aberration in telephoto photography and delivers a high level of sharpness even in the peripheral regions. The result is a lens that effectively compensates for axial chromatic aberration and magnification aberration throughout the entire zoom range and guarantees the highest resolution and brilliance for your pictures.
|Angle of View (diagonal)||78°45’ - 31°11’|
|Lens Construction||16 elements in 13 groups|
|Minimum Focus Distance||0.27m|
|Max. Magnification Ratio||1:4.5|
|Diaphragm Blade Number||7|
|Standard Accessories||Flower-shaped lens hood, Lens caps|
|Compatible Mounts||Canon, Nikon, Pentax, Sony|
Specifications, appearance, functionality, etc. may be changed without prior notice.
MTF (Modulation Transfer Function) curves describe to what extent the tested lens can faithfully reproduce contrast of the subject in images it captures.
The closer the 10 lp/mm (line pairs per millimeter) curve (the thick line for low frequency) in an MTF chart to "1" of the vertical axis (the higher up), the higher the contrast reproduction performance of the tested lens will be. The closer the 30 lp/mm curve (the thin line for high frequency) to "1" (the higher up), the higher the resolving power and thus the subjective sharpness of the lens will be.
Lens performance differs depending upon directions. Solid lines show performance in the sagittal (radial) direction while dotted lines indicate performance in the meridional (circumferential) direction. When sharp lenses capable of delivering uniform optical performance over the entire image field are tested, MTF charts show curves plotted in good balance.
Performance characteristics of photographic lenses cannot be expressed with only MTF charts. There are other factors that are expressed in different methods, such as taste of softness and degrees of compensation of various aberrations. But you can use MTF charts as a scale to measure lens performance.