For the price it is top amongst its rivals.

Excellent image quality

Would be even better with Image Stabalization

Getting the Canon 400 5.6L raised the quality expectation I had of camera lenses, immediately getting rid of the three I already had which now didn't seem up to the job. The choice was between this and the Canon 100-400mm and don't regret buying this as I've only once found I would have liked to...

VERY sharp; light; fast focus; use with converter; lightweight; quality build

None

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

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

I bought this lens from amazon to use with my 30D primarily for wildlife,bird protography. I was absolutely impressed how sharp the pictures came out from this combo of my 30D + 400 f/5.6 lens. I went to the SF zoo one day, took pictures of the birds that were on display from about 12-15 feet.

ultra sharp autofocus; very light; hand holdable; in-built retractable hood; L series; tack sharp images; fine glass; comes with tripod mount,sexy white color

f/5.6 is a bit small for low light; autofocus hunts in low light; not a 500mm lens :

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

Innan jag köpte den här gluggen så läste jag allt som fanns istort sett och alla berömde den. Det jag läste var sant. Jag har inte en gång varit missnöjd med den utan allt är bara kanon. Funderade länge på en 100-400 L och lyckades låna en för en stund.

Skärpan; lätt och smidigt; oerhört snabb autofokus

inga som jag märkt

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

"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.

Lens focuses very fast and accurate, great for birds in flight and other wildlife, light enough to carry all day and use hand held. However this lens is slow so it needs a lot of light. Wish canon would make the same lens with IS at a price mortals can afford.

extremely fast focus and light weight

needs lots of light to perform well