Resolution has always been my highest priority and this lens certainly is the best. The auto-focus features are superb. After using the 600mm f/4 L lens for years trading it in for the 800 was the best trade I've ever made.

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

wish it had a larger aperture

A great performing lens when it comes to Wildlife and news photojournalism. Of course you can use this lens for sports as well. But it might be a bit tight standing at the field, because you might be too close.

With the use of my lenshide and this Super Telephoto lens I did capture photos of wildlife that is so crisp and stunning. I pair this one with my canon 1DX because I observed that my 1DX give me more freedom with the light in low light situation. However, I sometimes I used also my 5DS.

The images produced at f5.6 are sharper than anything from any lens I've ever seen. Color and contrast are both excellent. Focus is fast and accurate. A keeper!

Really brings distant wildlife up close. Birds in flight are fantastic.

Consistent Output; Fast / accurate auto-focus; Sharp; Strong Construction

Really brings distant wildlife up close. Birds in flight are fantastic.

Consistent Output; Sharp; Strong Construction; Fast / accurate auto-focus

I have been using this lens for more than a month now. Its really exciting to see distant birds and wild animals so close thro' the image finder. AF is very fast.

Consistent Output; Durable; Easily Interchangeable; Fast / accurate auto-focus; Nice Bokeh; Rugged; Strong Construction

Heavy

What can I say, superb image quality with ultra long reach The ultimate wildlife lens, lighter than the 600mm and it fits (just) in my AW Rover bag so I can take it as hand luggage Add a 1.4x on a 1d body and you have autofocus (centre only) to an incredible 1456mmm equivalent Expensive but you know...

the pros of this lens are well documented in various on line reviews,all i will say is that its not cheap but its worth the money. you really do get what you pay for.its easy to manage thanks to its relative lightweight and it produces very sharp images for a super telephoto lens,F5.6 and F8 are the...

SUPERB LENS,VERY LIGHT,VERY SHARP AND EXQUISITE CONSTRUCTION

None really,F4 would be sweet but it would then weigh a tonne.

Canon's EF 800mm f/5.6L IS USM lens is a 'big gun' in many ways. Weighing 4.5 kilograms and almost half a metre long with its lens hood attached, it's a challenge to shoot with. However, it also has a maximum aperture of f/5.6, which is outstanding for a lens with such a long focal length.