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.
During use, you can switch between auto and manual focus by simply sliding the focus ring forward or backward. It can even focus down to a minimum of 1.6' away. Further benefiting image quality is an eight blade diaphragm that will ensure smooth out-of-focus areas. It also comes with a case and has a 77mm front filter thread.
35mm focal length equivalent of 35.5-67mm
Aperture range of f/4.5 to f/32
Angle of view of 76° to 44.5° which equates to 61.5° to 36° on Pentax 645 digital cameras
Lens construction of 11 elements in 9 groups
Accepts 77mm threaded filters
Minimum focusing distance throughout the zoom range is 1.6'
Works with both film and digital formats
Aperture ring and focusing distance scale
Eight diaphragm blades for smooth out-of-focus areas