The Canon Ef 100-400mm f/4.5-5.6L Is Ii Usm lens is a rugged, long telephoto lens designed for professional photographers to use with full-frame Canon DSLRs. Redesigned incorporating the latest image stabilization, autofocus and lens design advances, this lens offers outstanding image quality and fast Af. An Air Sphere coating has been added to many of the lens's elements to reduce ghosting and flare. Sharp pictures are also possible thanks to the Optical Image Stabilizer, which is effective for four stops. What you should know about this lens: 1. Super optics: In addition to Air Sphere coating to promote reduce backlit flaring and ghosting, the lens has a fluorite element and one Super Ud (Ultra Low Dispersion) element, which corrects aberrations and improves sharpness, clarity, and color accuracy. 2. 4 stops of stabilization: Minimizing camera shake is especially important when using a long focal length, which exaggerates any shakiness. The Canon Ef 100-400's Ois has three selectable image stabilization modes (standard, panning and during exposure only). They are effective for up to 4 stops of exposure. 3. Fast, accurate autofocus: Canon has upgraded its Ultrasonic Motor (Usm) and high-speed Cpu with optimized Af algorithms and nearly silent Af. 4. Precise zooming: The rotating zoom ring lens you adjust zoom position. You can vary the tension on the zoom via a zoom torque adjustment, giving the zoom a custom feel based on your preference. 5. Great Bokeh: With 9 rounded diaphragm blades, the lens is designed to produce rounded specular highlights and smooth out-of-focus areas so your subject stands out better..