This is a large aperture high performance telephoto lens, which is newly designed and different from ealier FD300mm f/2.8 lens. Artificial crystal fluorite is used for the second lens element and UD (Ultra-low Dispersion) glass is used for the third lens element. They minimize secondary spectrum to eliminate color fringes, appearing at the edges of subjects. The superb image quality of this lens is highly evaluated as the best quality of any telephoto lenses by many professional photographers.