A premier 300mm lens, offering an extra-ordinarily large maximum aperture for its focal length, providing bright and easy-to-focus images in the viewfinder Internal Focusing (IF) design permits easy handling and quick, accurate smooth focusing without any extension in the lens barrel Extra-low Dispersion (ED) glass insures crisp images free of chromatic aberration The focusing ring can be preset so that it will stop at a particular distance setting for rapid refocusing Built-in telescopic "bayonet-type" lens hood and 360 degree rotatable tripod socket collar Weight: 5.5lbs Recommended teleconverters TC-301 and TC-14B