An excellent choice as a second lens, this full-frame 28mm wide-angle prime features a bright F2 maximum aperture and outstanding overall optical performance. Advanced optics and coatings with a 9-blade circular aperture deliver beautiful images. Internal focusing on a fast and quite linear actuator makes this lens ideal for both still and movie. Circular Aperture When 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 defocused points of light. alpha 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.