Sigma Art is a premium wide-angle lensWIDE-ANGLE LENSHas a short focal length, hence a field covering a wide angle, ideal for architectural, interior and landscape photography where the photographer may be unable to move further away from the scene to photograph it. Wide-angle lenses come in both fixed-focal length and zoom lens varieties. range with a fast maximum apertureAPERTUREAperture, shutter speed and ISO form what is known as the exposure triangle in photography. Aperture refers to an opening inside the lens, similar to the iris of your eye, that changes in diameter to control the amount of light that enters a camera. Aperture is expressed in f-stops: the lower the number, the larger the aperture, e.g. f/1.4 is larger than f/8. A larger (or wider) aperture allows more light to pass through the lens to the sensor (film) as a picture is taken, particularly useful in low-light conditions. A larger aperture also produces a shallower depth-of-field, and thus more background blur. that offers greater contrastCONTRASTThe difference between areas of different brightness levels in a photograph: A high-contrast image has a greater difference between light and dark areas, whereas a low-contrast image has a narrow range of tones. Contrast is used to direct a viewer’s attention to a photographer’s subject either with colour contrast (bold versus duller colours) or tonal contrast (bright versus darker tones). , sharpness and colour definition. Available for Canon and Nikon mounts.