A highly practical medium telephoto lens with superb delineationand portability. Images are sharp and clear at all apertures. Through computer simulations, the lens has been designed to give beautiful background blur. Since the front lens group does not rotate during focusing special filter effects are not affected. Specifications: focal length & maximum aperture: 85mm 1: 1.8 lens construction: 9 elements in 7 groups diagonal angle of view: 28º 30' Focus adjustment: rear focusing system with USM closest focusing distance: 0.85M/ 2.8 ft.; filter size: 58mm Max. Diameter x length, weight: 3.0" X 2.8", 15.0 oz./ 75.0 x 71.5mm, 425G