High-performance L-series super-telephoto lens series with built-in dual-mode Image Stabilizer (IS) function. Ultra-high image quality through new optical designs with Fluorite and UD Glass. World's highest AF speed with improved Ring USM (Ultrasonic Motor) and new algorithms for focus prediction with moving subjects. Magnesium alloy lens barrels for reduced weight & rugged reliability. Focal Length & Maximum Aperture: 600mm 1:4.0 Lens Construction: 17 elements in 13 groups Diagonal Angle of View: 4.10 degree Focus Adjustment: Inner focusing system with USM Closest Focusing Distance: 5.5m / 18 ft. Filter Size: 52mm Drop-In Max. Diameter x Length: 168.0 x 456.0mmWeight: 5360g