The Pentax smc FA 645 45-85mm f/4.5 Lens is a standard zoom lens capable of wide angle to short telephoto focal lengths equivalent to 35.5-67mm in 35mm format. The maximum f/4.5 aperture is constant throughout the zoom range, and it can stop down to a minimum of f/32. This is due in part to a lens construction of 11 elements in 9 groups.
