This is a high-end lens utilizing the new “UD (Ultra-low Dispersion) Glass” lens element with anomalous dispersion. By using two UD glass lens elements, the secondary spectrum that tends to occur in telephoto lenses is minimized, and excellent image quality can be obtained for the entire frame even at maximum aperture without any image distortion due to chromatic aberration.
Moreover, this lens employs a rear focusing system, which only moves the small rear lens group, and a vari-pitch focusing system, which moves the lens group quickly at shorter distances and slows down the motion at longer distances. This achieves smooth focusing in all shooting distances without changing the overall length of the lens.