Canon EF 100-400mm f/4.5-5.6L IS USM

L-series super telephoto zoom lens equipped with an Image Stabilizer. The fluorite and Super UD-glass elements largely eliminate secondary spectrum. The floating system also ensures high picture quality at all focal lengths. The Image Stabilizer has two modes and it is compatible with Extenders 1.4x II and 2x II.

Equipped with an Image Stabilizer, the Canon EF 100-400mm telephoto zoom lens makes it easy to capture the far-off action of fast-paced sports or zoom in for an intimate portrait with a blurred background. The lens offer such features as fluorite and Super UD-glass elements that largely eliminate secondary spectrum; a floating system that ensures high picture quality at all focal lengths; two Image Stabilizer modes; and compatibility with extenders 1.4x II and 2x II. The lens carries a one-year warranty.

Technical Details
* 100-400mm telephoto zoom lens with f/4.5 maximum aperture for Canon SLR cameras
* 2 Image Stabilizer modes make it easy to capture far-off action or close-in portraits
* Flourite and Super UD-glass elements largely eliminate secondary spectrum
* Compatibility with extenders 1.4x II and 2x II; 5.9-foot close focusing distance
* Measures 3.6 inches in diameter and 7.4 inches long; 1-year warranty
* Focal length: 100-400mm
* Maximum aperture: 1:4.5-5.6
* Lens construction: 17 elements in 14 groups
* Diagonal angle of view: 24 to 6 degrees
* Focus adjustment: Rear focusing system with USM
* Closest focusing distance: 5.9 feet
* Zoom system: Linear extension type
* Filter size: 77mm
* Dimensions: 3.6 inches in diameter, 7.4 inches long
* Weight: 3.1 pounds

The Digital Picture.com Says:

The Canon EF 100-400mm f/4.5-5.6 L IS USM Lens has an excellent focal length range that includes the longest focal length found in a Canon zoom lens - 400mm. This long focal length and focal length range combine with very good image and build quality to make the 100-400 one of the most popular serious wildlife and sports lenses Canon sells.

Canon Website Customer Review:

I had a hard time deciding between this and the 70-200L F2.8 and this lens. After trying out both and with my budget I went with the 100-400.
I shot nature, mostly wildlife and birds. Also shoot a lot of airshows. For me this is a great choice even though it is a slower lens it is very versatile.
I am very pleased with the results of this lens with my 40D. Coupled with the 24-105L I can shoot most situations that come up.