There’s little point in having a 50.6MP sensor if the camera can’t focus on the subject with pinpoint accuracy, and to this end Canon has fitted the 5DS R with what it boldly claims to be the best autofocus on the market today. The 61-point system includes 41 cross-type points and five double cross-type for extra accuracy with fast lenses. The central point also works with lenses that have an effective aperture of f/8, so it will continue to function with f/4 zooms fitted with a 2x teleconverter. As well as using a single AF point, it’s possible to select expanded groups of five or nine points.
In practice, I’ve found that the AF system goes a long way towards living up to Canon’s promises. No matter what lens I’ve used, from the 24-105mm f/4 zoom to the 35mm f/1.4 prime, it has acquired focus with unerring accuracy, even using focus points far off-centre (which are usually the least reliable). It’s also not required any micro-adjustment, which is unusual when shooting fast primes and makes life much easier for the user.
Switch to live view and autofocus is reasonably quick, which is welcome as this is traditionally not a strength of DSLRs. Even in poor light the camera usually finds focus in less than a second. This speed is very lens-dependent, but with the most amenable, AF is conceivably usable for handheld shooting. The focus area can be placed wherever you please across most of the frame, and the accuracy is excellent. Of course, if you’re shooting in live view using a tripod, then focusing manually using magnified display gives the best-possible results.