The Pentax 300mm f/4 ED(IF) AF lens for the 645 cameras is a high-quality telephoto lens featuring extra-low dispersion glass, internal focus and a rotating tripod collar for improved balance when mounted on a tripod or monopod.
Pentax lenses have been developed using the latest in computer-assisted optical design technology. Lens surfaces are treated with Pentax's exclusive Super-Multi-Coating for sharp, high-contrast images. ED(IF) lenses are super high performance lenses incorporating special Extra-low Dispersion (ED) lens elements to assure the highest image quality and minimize chromatic aberrations. The Inner Focus (IF) mechanism minimizes lens extension when focusing, maintaining good balance and assuring smoother focus ring operation and a closer minimum focus distance.