This is more lens you get for your money. Sharp wide open and hand holdable. If for birding (BIF), this lens can not be beat except for those by $$$$$.

Durable; Fast / accurate auto-focus; Hand Holdable; Lightweight; Nice Bokeh; Rugged; Sharp wide open; Strong Construction; You will not miss IS

NONE

This lens is light enough to carry comfortably in its case on a belt and/or with the shoulder strap and cheap enough for some of us to buy without a mortgage on the house. This is possible because it does not have IS and it is limited to an aperture of F 5.6, which are its cons.

Consistent Output; Durable; Easily Interchangeable; Fast / accurate auto-focus; Good quality case; Integrated lens hood; Lightweight; Nice Bokeh; Rugged; Strong Construction

No Image Stabilization; Poor in Low Light

how sharp do you want,i use hand held most times and get lots of keepers ,use a 1D MK111 no problems with this kit I use for Birds and surf sports, as good as the big bucks

Fast auto-focus; Superior build quality; Super-sharp images

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 am an extremely satisfied user of Canon 400 mm F 5.6 EFL lens. I have used this lens with variopus Canon bodies like Canon EOS 1RS, EOS 1N, EOS 3, EOS 1DS mark II, EOS 5D. I have had wonderful experience with all these bodies with excellent sharpness in the center of the frame.

Outstanding sharpness; well controlled flare characteristics; very little lateral colour; Minimal drop in sharpness with the 1.4 X EF teleconverter

lack of USM; I guess that is about it

"Primary use: Birding and wildlife Camera body: Canon 7D Pros: Great clarity of glass, relatively light (for a 400mm), sharp wide open at f/5.6, built in hood is so convenient (don't overlook this advantage), quality build, and price.

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

I am disappointed this is not the unit I thought I was buying. It was the only "L" USM 400mm f/5.6 CANON lens so silly me as I have ended up without image stabiliser & the item I wanted. I now note the "EF" may need to be "IS". Had I made a retail purchase I would have seen this

Never liked the EF 300 MM F4.0, the EF 100-400 mm was already better. But the 400 MM F5.6L surprised me. The IQ is very very good. For a short time I have had the EF 400 F2.8 ISL. The IQ of that lens is out of this world, as is the weight. You need a truck to get where you want to take your photo's.

Light; build-in hood; very nice IQ; nice Bokeh; cheap; 800 euro for a second hand

No IS; F5.6 with extenders makes it F8.0

Excellent lens! Outstanding pictures! Great wildlife and landscape lens! Very satisfied! Canon L lenses are always top of the line! Recommend highly!