10-20mm F4-5.6 EX DC lens allows enjoyment of super wide-angle photography and it is a very powerful tool for indoor shooting and landscape photography with APS-C size image sensors of digital SLR cameras.Wide angle of view (102.4 ? at 10mm and 63.8 ? at 20mm) offers the photographer greater freedom of expression. Three SLD glass elements are employed for effective compensation of color aberration, which is a common problem with super-wide angle lenses. One piece of glass mold and two hybrid aspherical lenses, offer excellent correction for distortion, as well as all types of aberration.This lens is equipped with an inner focusing system. It has a minimum focusing distance of 24cm (9.4") at all focal lengths. The non-rotating lens barrel perfectly suits the petal shaped lens hood. A circular polarizing filter can also be used conveniently.