The only non-image stabilized offering of the three 400mm lenses Canon has, produces excellent images. This is a good lens for wildlife photography, especially on a cropped sensor Canon, which makes this lens a 640mm equivalent. The built-in hood is a nice alternative to the plastic ones you have to put on yourself (and remember to carry with you!), but it does add to the weight a bit, if that's a consideration. Canon includes a tripod ring, another good move on Canon's part, saves you an accessory to buy separately. But the lack of IS is a bit of a limitation for me, as the size and weight of the lens makes handholding it a problem - hand shake blur is evident except for shots taken in the very brightest of conditions. If handholding the larger lenses causes you problems in general, you might want to consider springing for an image-stabilized alternative. Otherwise this lens is a strong performer and I've been happy with it.

It's hard to find as long a lens at a comparable price, but there is a "you get what you pay for" factor. Of all of my Canon lenses (I have seven), this is the softest and offers the least contrast. It performs best in bright light when you can stop it down to f/14 or better. I have used the 400mm lens with both the 1.4x and 2x Canon extenders (1.4 is better). It's a comparatively slow lens. BUT the 400mm f/2.8 is over $5000 more! So you can see why "bang for your buck" means something. Also, this is a _much_ lighter weight lens than the faster Canon telephotos. Finally, it is not image stabilized, so you will likely want to a solid tripod or monopod.

On balance, if you don't need the very finest optical quality, this lens is well-worth the price.

The 5.6 aperture limits this lens for mostly outdoor photography, but then again, how often do you need a lens of this capacity for indoor purposes. I used this lens for some high school football games and to photograph buildings in the distant. The results are amazing with stunning clarity. If only it wasn't so heavy and large in size, but, I guess it could be worse.

I have been using the Canon 400mm f5.6L lens for well over a year now mainly for wildlife photography, and the lens was worth every penny I paid for it. Built tough, the image quality coming out of this lens is exceptional: sharp as a tack even at f5.6 with exceptional contrast and clarity. Relatively lightweight makes for an exceptional walk around lens, and in a good deal of conditions given its focal length and weight it can be handheld. A great lens for the price.

I am very happy with this purchase. The extremely fast auto-focus makes catching shots I am after much easier than with any other lens I currently own. I highly recommend it, especially for nature photography.