Sharpness diminished with my second-generation Canon 1.4x extender attached, but I was still impressed. And the hassle of putting on the extender, in particular with a lens this large, made me appreciate the convenience of having one built in all the more.
The lens, a member of Canon's high-end L-series family, is admirably sturdy, with seals to protect against water and dust. The operation of all the controls is easy, with comfortable ribbed rubber grips for zoom and focus.
On the lens barrel are a lot of switches for a lens. Closest to the camera is a switch to set the lens focus range -- either the full range, 2 to 6 meters, or 6 meters to infinity. Next to that switch is the autofocus setting: autofocus, manual focus, or the newer power focus, a movie-oriented feature that uses a motor to smoothly change the focus.
|Focal range||200-400mm without 1.4x extender; 280-560mm with extender|
|Aperture range||f4 without extender; f5.6 with extender|
|Minimum focus distance||6.5ft/2m|
|Angle of view||6.2-12 degrees without extender; 4.4-8.8 degrees with extender|
|Elements||25 without extender, including fluorite and ultra-low dispersion glass; 33 with extender|
|Coating(s)||fluorine on front and back elements for dirt resistance; SWC (subwavelength structure coating) to cut flare and ghosting|
|Filter diameter||52mm drop-in|
Farther out on the barrel is the switch for choosing stabilization modes: 1 for full image stabilization, 2 for vertical-only stabilization for panning shots, and 3 for engaging stabilization only after you've pushed the shutter release button. Here you can also set a an autofocus preset that's useful when you can predict a subject's distance -- the point on a track where a race car comes into view, for example, or the watering hole on a safari.
The lens is well suited for sports and wildlife photographers who benefit from some flexibility. Those who specialize in birds might well be better off with Canon's 500mm or 600mm f4L lenses, perhaps augmented with a 1.4x telephoto extender. Birds, unless comfortable around humans, are generally small, fast-moving, and far away. That means the 200mm end of the 200-400mm lens' range isn't terribly useful, and f5.6 is a notch slower when you're at maximum telephoto.
Just getting the lens out into the field is an ordeal. It comes with its own suitcase and shoulder strap, but I found it more convenient to reconfigure my unusually large camera backpack. Most camera daypacks won't be able to hold it, though.
Many photographers in the market for a lens like this will already have sturdy tripods, gimbal mounts, and big packs, but if you don't, the high cost of this lens will be supplemented by some expensive accessories. Compared to the cost of the lens itself, though, it's pocket change.
The price is easier to stomach when you think about what it would cost to stretch from 200mm to 560mm so rapidly. To handle that range without the laborious process of attaching a teleconverter, you'd need two camera bodies and two lenses. Even with more affordable options, such as the $1,700 100-400mm or Canon's $1,340 EF 400mm f/5.6L USM with a 1.4x extender attached, you're talking about thousands of dollars, an aperture of f8 at 560mm, and a lack of image stabilization at the long end that puts more limits on your shutter speed.
Other options are Sigma's 150-500mm F5-6.3 APO DG OS HSM or its $1,000 120-400mm F4.5-5.6 DG APO OS HSM with a teleconverter. These are geared more for consumers, though, and come with compromises in sharpness and aperture.
Perhaps the best alternative would be to get a crop-frame camera body such as Canon's 7D or new 70D and the Canon 100-400mm. With the 1.6x focal-length multiplier, you'd be looking at an equivalent of 160-640mm, and you won't suffer the autofocus limitations of shooting at f8.
There's no question what the most desirable option is, though: the superb image quality and supertelephoto flexibility of Canon's extendable 200-400mm. It's no wonder Canon is charging a premium.