Pros: I have had numerous favorable photography gear purchases from buydig.com and my new Canon 400mm 5.6L is no exception. It's a sharp, telephoto lens with a wonderful bokeh not to mention it is rather light weight. So it's easy to carry by hand vs. requiring a tripod.

I bought this to replace another lens that failed several years ago, so I have had plenty of experience with it shooting various wildlife, primarily birds for large prints, typically up to 36 inches on a side, using a Canon 40D, then a 60D.This lens is capable of extremely high IQ images.

Consistent Output; Durable; Easily Interchangeable; Fast / accurate auto-focus; Lightweight

Maybe Soft Wfilters; Maybe Soft W Filters

A good entry level bird/wildlife lens. Takes a bit of practice to get sharp shots handheld.

Well made; Sharp; Not too heavy for a 400, but not exactly light either; Good value; Works pretty well with the 1.4x extender; Fast autofocus

It could really use IS

I purchased this lens for bird photography and am very happy with it so far. It is lighter than the 100-400mm Canon and have found that all my pictures are at 400mm anyhow. The lack of IS might be a problem for some especially in dusk/dawn situations when you need to slow the shutter down.

Durable; Fast / accurate auto-focus; Lightweight; Rugged; Strong Construction

Poor in Low Light

Brilliant optics, tack sharp wide open with aps-c , razor sharp on FF !! Wish canon had added IS to it to compensate for the slow aperture.

A very fast focusing lens on canon. MTF chart of the lens says all about the picture quality

This lens is one of the great values in photography. It is super sharp and does a great job of bringing the action to you. While it does not have image stabilization, it is light enough to hand hold and with some practice you can get great shots.

Image quality; weight; build quality

No image stabilization; maximum aperture f/5.6

I bought this for a trip to BC/Alaska, and it's my first Canon L lens. It may have cost me an arm and a leg, but it is solidly built and focuses very fast. I bought a monopod at the same time but it could really do with a pistol grip screwed into the lens's tripod bush when you're shooting hand-held...

This is the ultimate best birding lens for hobbyist photographers. I agree, in theory the EF 300mm f/4L IS + 1.4x extender should be better but actually it isn't as per users' opinions. I have owned this lens for 17 months and shot thousands of images with it mounted on my EOS 450D and EOS 50D.

a; Lightweight b; Affordable c; Sharp d; Fast autofocus

a; Lack of weather sealing

I'm using this lens and an EOS 700D on an internet controlled astrograph. The build and the image quality over the entire field are both absolutely superb. Ultimate picture quality appears to be limited by the camera sensor, rather than the lens. Just amazing. Next, a x2 extender.