Canon EF 400mm f/5.6 L USM + x2 Converter

Does anyone have experience using a x2 converter and Canon EF 400mm f/5.6 L USM? Will I be able to auto focus using an up to date firmwared 5DMK3? Or would it be best to use a x1.4 instead. I've read loads on the Net and still haven't got a definite answer.

Many thanks

I've used it and it's doable although not the best. The quality as you can expect drops, and more chromatic aberration shows up. For objects relatively close and without heat haze its actually decent, but I doubt you will get AF with it, it didn't work with my 6D.

These 2 photos were with the 2x.

https://www.flickr.com/photos/janjasinski/9811042784/in/set-72157626186279771

https://www.flickr.com/photos/janjasinski/9805898535/in/set-72157626186279771

Many thanks Jan,

I'd be using it primarily for some extra reach at airshows (I use 100-400 at the moment) so the lack of autofocus for moving objects makes it a no goer.

Anyone using Kenko converters, do these work better than Canon versions?

I'm led to believe the Canon x1.4 works OK and with the latest 5D firmware, has autofocus?

hoping for some more feedback...cheers

the converter will only normally work with the 1D series cameras if you want the A/F to operate normally, quality still wont be great though as you will also lose stops

This post has been edited by Darryl Morrell on 2nd September 2014 - 20:01

I heard the Kenko's are good, better than Canon even. The 1.4 will AF, but the 2x not sure.

I have used the Kenko 1.4x with the 70-300 f/4-5.6L. On a full frame (my 6D) it autofocuses perfectly at 420mm and f/8 (example: http://www.airplane-pictures.net/photo/345515/n218jb-jetblue-airways-embraer-erj-190-190-100/) . On a crop body (my 60D) it generally will not focus at 420mm with that lens (it is f/8 at full zoom extension). It will autofocus most of the time, on a crop camera, until about 350 or 375mm (in other words, when aperture is smaller than 5.6 but not quite f/8). You lose some sharpness and there is some increased chromatic aberration, but it's still usable. I just uploaded a shot made with the Kenko 1.4x attached (http://www.airplane-pictures.net/photo/453080/vt-alq-air-india-boeing-777-300er/)

Thanks for the feedback everyone, some decisions to make now I'm better informed.

For auto focus and extra reach I need I think I may well have to stretch the budget for a second hand/used mk1 500mm, although there's not that many on the market at the moment.

thanks again