Canon offers a medium telephoto lens with built-in softfocus function. While providing sharp high-quality telephoto performance for normal use a molded glass (GMo) aspherical lens element (4th) moves for spherical aberration generating to vary the degree of softfocus effect. This design provides a superb softfocus effect while at the same time precisely corrects changes in aberration due to changes in focusing distance. Softfocus effect is ideal for portrait and pictorial scenes. Two degrees of softfocus can be selected. The AF system precisely focuses the subject for the optimum softfocus effect.