This Canon telephoto lens with a rear-group focusing system unique to Canon is designed to deliver extra high-quality performance. In the rear-group focusing system, only the smaller-diameter rear lens group moves during focusing; the front lens group remains stationary. This system assures very smooth focusing and a compact, well-balanced lens. Therefore, operation is greatly improved.
SPECIFICATIONS Type: super telephoto. Construction: 6 elements in 5 groups. Angle of view: 5 degrees 10 seconds. Minimum Aperture: F/32. Closest Focusing Distance: 13ft. Filter size: 34 drop-in with holder. Lenshood: built-in. Length: 11.3 in. Weight: 2lbs 8oz.