A New And Affordable L-series Ultra-wide-angle Zoom Lens That's Ideal For Both Film And Digital Slrs. Superior Optics Are Assured By The Use Of Three Aspherical Lens Elements, In Addition To A Super Ud (ultra-low Dispersion) Glass Element. Optical Coatings Are Optimized For Use With Digital Cameras. This Lens Focuses As Close As 11 (0.28m), And Offers Both Canon's Full-time Manual Focus And A Powerful Ring-type Usm For Fast And Silent Af. It Has A Constant F/4 Maximum Aperture, And Offers The Choice Of Screw-in 77mm Filters Or A Holder In The Rear Of The Lens For Up To Three Gel Filters. Finally, It Offers Weather-resistant Construction Similar To Other High-end L-series Lenses.