Progressive Winner CANON EOS R

IF YOU’RE OLD ENOUGH TO remember when autofocusing in SLRs was finally perfected, Canon and Nikon did things very differently. Nikon opted for body-based AF motors, Canon put them in the lenses which, of course, necessitated a new lens mount. It caused a fair amount of grief at the time, but has ultimately been proven right, although Nikon did find ways of making its venerable F mount work right up until now (albeit with gradually diminishing backward compatibility).

The two brands have essentially always done things differently – particularly as far as pro-level cameras are concerned – ever since Canon launched its F-1 to compete with Nikon’s F back in the early 1970s. Those two cameras were very different too. Over the decades it’s resulted in “Canon people” and “Nikon people”, two fiercely-loyal tribes whose members have rarely been convinced to swap sides. And, as all the many other brands who have had a stab at the pro market have discovered, are even less likely to stray outside the duopoly.

So here we are at the start of another new era in pro cameras and there some key points of difference in how Canon and Nikon have tackled the design of their full-35mm mirrorless camera systems.

Of necessity, both employ all-new lens mounts with, now that the reflex mirror is gone, much shorter flange back distances than their existing D-SLR fittings. Both camera makers are emphasising the increased possibilities in lens design that their new mirrorless mounts will enable, although it’s interesting to note that the inner diameter of Canon’s new RF bayonet fitting is the same as that of the EF mount, indicating that there was a fair amount of forward thinking going on when it made its debut back in 1987. Given the disruptions caused by introducing a new lens mount (although it’s less problematic now than previously), both systems include an adapter which maintains a high degree of compatibility with the current D-SLR systems, although Canon has gone further here, offering three options (more about these shortly).

The new RF mount retains a three-claw mechanical configuration and has the same internal diameter of 54 millimetres as the EF mount, but the flange back distance is reduced to 20 millimetres (compared to 44 millimetres). There’s a total of 12 communication pins for faster communications between camera body and lenses (up from eight on the EF mount).

For the record, Canon now has four lens mounts in play (EF, EF-S, EF-M and RF), but interestingly the two mirrorless fittings aren’t compatible as EF-M has an even shorter flange back distance of 18 millimetres. Consequently, there’s no adaptor for EF-M lenses, but there’s a choice of three for fitting EF and EF-S types (and, unlike the D-SLRs, the camera automatically switches to ‘APSC’ format with the latter). In addition to the standard EF-EOS R mount adaptor, one adds the multi-function control ring that’s a feature of all the RF mount lens and the other incorporates a drop-in filter holder and is bundled with either an ND filter or a circular polariser. Canon says that over 70