Full-frame fisheye images with an angle of view of 180° across the diagonal of the 24mm x 36mm picture format. Startling pictorial effects are possible because of extreme barrel distortion, virtually unlimited depth of field, and exaggerated perspective rendition. Fast f/2.8 maximum aperture produces bright images in the viewfinder, making it easy to focus accurately even in dim light. High contrast images even at full aperture are assured because this lens is extremely well corrected for chromatic aberration. Standard equipment includes a built-in scalloped lens hood to minimize flair when shooting against the light and a set of 4 filters (skylight, orange, light amber, and light blue) which bayonet onto the back of the lens.Focal length/ Aperture- 16mm f/2.8, Lens construction-8 elements in 5 groups. Distance scale- Graduated in metres and feet from 0.3m (1ft) to infinity (∞).