The AT-X 300 AF PRO is a wide aperture telephoto lens, which provides high definition and super sharpness even with the aperture wide open at f/2.8. Two large SD glass elements in the first optical group correct chromatic aberrations and create accurately focused color. This exceptional optical performance is maintained down to its minimum focus distance of 8 feet (2.4 meters). The external textured armalite finish and rubber grips improve handling as well as adding a distinguished look to this performance lens.
The patented IRF (Internal Rear Focusing) system yields quick and reliable auto focus by only moving smaller elements in the rear of the lens to achieve focus. The nine bladed aperture creates a more circular light path which in turn gives more even illumination across the frame, reduced diffraction at small apertures provides more pleasing appearance to out of focus highlights.