Focal Length & Maximum Aperture:Built-in extender at 1x: 200-400mm 1:4.0 Built-in extender at 1.4x: 280-560mm 1:5.6Lens Construction:Built-in extender at 1x: 25 elements in 20 groups (incl. 1 rear filter) Built-in extender at 1.4x: 33 elements in 24 groups (incl. 1 rear filter)Diagonal Angle of View:Built-in extender at 1x: 12°-6°10' Built-in extender at 1.4x: 8°50'-4°25'Focus Adjustment:Inner focusing systemClosest Focusing Distance:6.6 ft. / 2mFilter Size:52mm drop-inDimensions (WxHxD):5 x 14.4 x 5'' (127 x 366 x 127mm)Weight:8 lbs (3.6kg)・High performance L-series super-telephoto zoom with built-in 1.4x extender (280 560mm f/5.6) makes it ideal for sports and wildlife photography.・One fluorite and four UD lens elements provide excellent correction of chromatic aberration throughout the entire zoom range delivering high-quality images with high resolution and contrast.・Inner focusing ring USM a high-speed CPU and optimized AF algorithms for fast and accurate autofocusing.・Optical Image Stabilizer provides up to four shutter speed stops of correction.・Three image stabilization modes (standard panning and during exposure only) provide excellent results for a wide range of shooting situations.・Optimized lens placement and coatings deliver outstanding color balance while helping to minimize ghosting and flare.・Highly resistant to dust and water enabling shooting even in harsh conditions.・Circular aperture (9 blades) helps delivers beautiful soft backgrounds.・Fluorine coating on front and rear lens surfaces reduces smears and fingerprints.・Power Focus mode enables smooth focus shifts essential for filmmaking.Designed to satisfy the discriminating needs of sports and wildlife photographers the Canon EF 200-400mm f/4L IS USM Extender 1.4X is a high-performance super telephoto zoom lens with an optically matched built-in 1.4x extender for maximum versatility. With a simple flick of a switch the zoom range can be quickly increased to 280-560mm (f/5.6). This capability is extremely useful in applications where it is not possible to change lenses quickly while also protecting delicate equipment such as a digital SLR camera's image sensor in environments with dust and high humidity. The EF 200-400mm f/4L IS USM Extender 1.4X incorporates one fluorite and four UD lens elements which provide excellent correction of chromatic aberration throughout the entire zoom range for professional quality images with high resolution contrast and color fidelity while a 9-blade circular aperturehelps deliver beautiful soft backgrounds. It utilizes inner focusing ring USM a high-speed CPU and optimized AF algorithms for fast and accurate autofocusing. And with Power Focus mode focus shifts are quiet and smooth which is essential for filmmaking. Image stabilization is effective up to four shutter speed steps with three image stabilization modes (standard panning and during exposure only) providing excellent results for a wide range of subjects. Optimized lens placement and coatings deliver outstanding color balance while helping to minimize ghosting and flare. The lens is highly resistant to dust and water enabling shooting even in harsh conditions. A fluorine coating on front and rear lens surfaces repels dust particles and makes the lens easier to clean.The Canon 200-400 is commonly used for Sports/action Wildlife photos and more.The Canon 200-400 is popular because customers like the following qualities of the Canon 200-400: Consistent output Fast / accurate auto-focus Rugged and Strong construction.