|This compact, lightweight lens offers a very useful 18mm through 55mm zoom range on cameras with APS-C size sensors (27 mm ~ 82.5 mm equivalent in 35 mm full-frame format). Two aspherical elements and one ED glass element minimize aberration and the SAM driven autofocus mechanism has also been refined for even smoother AF operation.|
Circular ApertureWhen changing your aperture to defocus the background, the light sources appear blurred. This ‘bokeh’ effect of the blurred background can be enhanced with circular aperture blades used in this lens. Conventional aperture blades have flat sides creating unappealing polygonal shaped defocussed points of light. α lenses overcome this problem through a unique design that keeps the aperture almost perfectly circular from its wide-open setting to when it is closed by 2 stops. Smoother, more natural defocusing can be obtained as a result.
ED (Extra-low Dispersion) glassAs focal lengths get longer, lenses built with conventional optical glass have difficulties with chromatic aberration, and as a result images suffer from lower contrast, lower color quality, and lower resolution. ED glass dramatically reduces chromatic aberration at telephoto ranges, and provides superior contrast across the entire image, even at large aperture settings. Super ED glass provides enhanced compensation for chromatic aberration.
Aspherical lens elementsAspherical lens design dramatically reduces spherical aberration while also reducing lens size and weight. Spherical aberration is a slight misalignment of the light rays projected on the image plane. This is caused by differences in refraction at different points on conventional spherical lenses which degrade image quality in large-aperture lenses. Specially shaped “aspherical” elements near the diaphragm restore alignment of light rays at the image plane, maintaining high sharpness and contrast even at maximum aperture and can also be used at other points in the optical path to reduce distortion. Well-designed aspherical elements can reduce the total number of elements required in the lens, thus reducing overall size and weight. Advanced Aspherical (AA) elements are an evolved variant, featuring an extremely high thickness ratio between the center and periphery. AA elements are exceedingly difficult to produce, relying on the most advanced molding technology to consistently and precisely achieve the required shape and surface accuracy, resulting in significantly improved image accuracy and quality.
SAM (Smooth Autofocus Motor)Rather than using the focus drive motor in the camera body, SAM lenses feature an autofocus motor built into to the lens itself that directly drives the focusing element group. Since the built-in motor directly rotates the focus mechanism, operation is significantly smoother and quieter than conventional coupled autofocus drive systems.
|Lens Mount Type||Sony A-mount|
|Focal Length (35mm equivalent)||35mm equivalent focal length (APS-C) 27-82.5mm|
|Filter Diameter||55 mm|
|Lens Groups-Elements||8 elements in 7 groups|
|Minimum Focus Distance||9" (0.25m)|
|Aperture Blade||7 blades (circular aperture)|
|Aspheric Elements||3 elements including 1 ED element|
|Focal Distance||Min. 10” (0.25 m)|
|Weights and Measurements|
|Dimensions (Approx.)||2-7/8 x 2-3/4” (71.6 x 69mm)|
|Weight (Approx.)||7.9 oz (222 g)|
|Service and Warranty Information|
|Limited Warranty Term||1 year parts and labor|
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