Reunion Lundi 9 Janvier 2012

First, the new Canon EOS 1D X, unlike previous 1-Series DSLRs, will not autofocus when using lenses or lens combinations with an f/8 max aperture. Chuck Westfall (Canon USA), through Arthur Morris, confirms this: "AF is unavailable on the EOS-1D X if the maximum aperture reported to the camera through the electronic lens mount is smaller than f/5.6."

This is of course disappointing to many extender users. Canon does not currently have a bare lens with a max aperture narrower than f/5.6, but adding a 1.4x extender to an f/5.6 max aperture lens results in an f/8 max aperture lens that will no longer AF. And, adding a 2x extender to an f/4 max aperture lens results in an f/8 max aperture lens that again will not AF.

The largest group of photographers affected by this change are, probably, bird photographers (such as Arthur Morris) - who have been dealt a double blow with the 1D X. Bird photography typically needs the most reach possible - through both lens focal length and sensor density. Increasing focal length via extenders has now been limited (for autofocus to function) and the 1D X has a less-dense sensor than either of the previous 1-Series models.

As I said early in the Canon EOS 1D X review, there is no AF with lenses and lens combinations that report an aperture narrower than f/5.6. To be more clear, f/8 max aperture lens plus extender combinations will not AF on the 1D X. An f/5.6 lens with a 1.4x extender or an f/4 lens with a 2x extender will not AF on the 1D X. This is, perhaps, the end of that era. I have to admit that I'm surprised by this design decision. I hope that the overall AF benefits far outweigh the loss of f/8 AF.

Currently, only Canon 1-Series bodies can autofocus with an f/8 max aperture lens (typically a lens + extender combination). Only the center AF point is functional at f/8.