The 500mm f/4.5 is the "big brother" to Mamiya�s ground breaking 300 f/2.8 APO for the 645 Series. Designed with ultra low dispersion glass, the 500 APO fully corrects for chromatic abberation, assuring superb sharpness and colour reproduction at all apertures. It is designed for use with the 2x Tele Extender for use as a 1000mm hood and hood extension, and drop in filter set. Equivalent to 310mm in 35mm format.     500mm f/4 APO Optical Construction 11 elements / 9 groups Angle of View 8 Degrees Minimum Aperture 32 Diaphragm Automatic Minimum Focusing Distance 16� 5.0�/500cm Maximum Magnification Ratio 0.11X Area Covered 14.9 X 20.1� / 377 X 509mm Equivalent 35mm Focal Length 310mm Filter Size Drop in (6 types) Lens Hood Built in with extra hood Dimensions (L XW) 14.9 x 6.4� / 377.5 x 162mm Weight 11lbs. 15oz. / 5,410g J.P. Code 901093 Mamiya Code 302330