The Sigma Super Wide Angle Zoom 18-50mm lens offers a large aperture of F2.8 over its entire range of focal lengths and its large depth of field offers greater freedom of creative expression. This lens is perfectly suited for low light conditions indoors or at dusk. It covers wide angle to medium telephoto and is ideally suited to a wide range of subjects. It is an ideal large aperture standard zoom lens for digital SLR cameras featuring APS-C size image sensor.
The characteristics of digital SLR cameras were taken into consideration when designing the lens power layout. A Special Low Dispersion (SLD) glass lens element provides effective compensation for lateral chromatic aberration, which is likely to occur with digital SLR cameras. The use of two aspherical lens elements provides correction for various aberrations and makes high quality images a reality throughout the entire zoom range.
A Special Low Dispersion (SLD) lens and two aspherical lens elements provide excellent correction for all types of aberrations. The design produces a compact and lightweight, yet robust, construction with an overall length of 84.1mm (3.3in.) and maximum diameter of 74.1mm (2.9in.) and weight of 445g (15.7oz).
Super Multi Layer (SML) coating gives the best color balance and reduces flare and ghosting from which digital cameras tend to suffer. This lens has a minimum focusing distance of 28cm (11 in.) throughout the entire zoom range which is very convenient for close-up photography. The lens is equipped with an inner focusing system. The non-rotating front lens element makes the lens suitable for using its petal-type lens hood and circular polarizing filters. This lens has excellent correction for vignetting which is a common problem of large aperture lenses. Its new design ensures superior peripheral brightness.
Lens Technology Explained:
ASP (Aspherical Lens)
The aspherical lens complex allows freedom of design, improved performance, a reduced number of component lenses and a compact size.
IF (Inner Focus)
To ensure stability in focusing, this lens moves the inner lens group or groups without changing the lens' physical length.
EX (EX Lens)
The exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance.
DC for Digital (DC Lens)
These are special lenses designed so that the image circle matches the smaller size of the image sensor of most digital SLR cameras. Their specialized design gives these lenses the ideal properties for digital cameras, the compact and lightweight construction is an added bonus ! including compact and lightweight construction.
Lens Construction: 15 Elements in 13 Groups
Angle of View: 69.3 - 27.9 degrees (SD format)
Number of Diaphragm Blades: 7 Blades
Minimum Aperture: F22
Minimum Focusing Distance 20cm/7.9 in.
Maximum Magnification: 1:3
Filter Size Diameter: 72mm
Dimensions: Diameter 79mm x 85.8mm / 3.1 in. X 3.4 in.
Weight: 450g/15.9 oz.