Pentax DA645 28-45mm F4.5ED is an Auto Focus (AF) Wideangle Zoom lens with 645 max sensor coverage. When mounted on a 645 sensor camera, it will give you an FF equivalent focal range of 21.84mm. With the max apertures of only f4.5 at 28mm, and f4.5 at 45mm, the lens is quite slow at both ends.
This lens features on optical image stabilization which helps capturing sharper images at lower shutter speeds. Pentax DA645 28-45mm F4.5ED is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.