Product Description
EF mount; telephoto lens Ultra-low Dispersion glass with Fluorite elements; inner focusing ring; full-time manual focus; image stabilizer 300mm focal length f/4 maximum aperture Micro UltraSonic Motor (USM)
From the Manufacturer
Bring your subjects closer while shooting sports or wildlife with the Canon EF 300mm f/4L telephoto lens. The lens is equipped with Image Stabilizer (IS) technology, which compensates for camera shake by providing the equivalent effect of a shutter speed two stops faster. The camera provides two IS modes: Stabilizer 1, the same mode featured on the EF 75-300mm lens, and Stabilizer 2, which steadies the image during horizontal or vertical panning. The lens is also half the weight of the 300mm f/2.8L IS, with a close focus distance of 4.9 feet. And like all of Canon?s fixed focal length L-series lenses above 135mm, it?s compatible with Canon's EF 1.4x II and 2x II Extenders.

Specifications
Focal length: 300mm
Maximum aperture: f/4L
Lens construction: 15 elements in 11 groups
Angle of view: 8 degrees @ 15 feet
Focus adjustment: Rear focusing system with USM
Closest focusing distance: 4.9 feet
Filter size: 77mm
Dimensions: 3.7 inches in diameter and 8.7 inches long
Weight: 2.6 pounds