New Canon patents published this week show Canon working on new super telephoto designs for the RF mount. The existing RF 400mm f/2.8 and 600mm f/4 “big whites” are actually the older EF designs coupled with an adapter. These new designs include a 200-500 f/4 and a 300-800 f/8.
Also included in the patent are 150-600mm and 200-400mm variants. They really covered all the bases in terms of super telephoto zoom ranges.
Both of the larger lens designs are about a half meter in length and would have fairly wide objective lenses, making these about the same size class as (but larger than) the current 200-400 f/4. The designs show a set of lens elements numbering about a couple dozen, with numerous aberration correcting sets.
The theoretical correction effect is notable, with charts given in the patent document showing the sort of lack of spherical aberration, astigmatism and chromatic aberration seen previously only in Canon’s best lenses. Distortion is slightly less corrected, but Canon nowadays tends to rely some on in-camera computational modification to bring that home.
These patents are added to a previously-published set of patents for supertelephoto primes made public just about a year ago. While these new patents came out later, they may prove quicker to market – if they ever do make it to market – because Canon opted to re-use its EF lens designs when it produced the RF 400mm and 600mm primes. Canon very seldom releases a new version of those lenses without at least four years passing first. The zoom lenses listed in the current patent don’t have equivalent Mark I lenses in Canon’s current line-up, aside from the now-long-in-the-tooth EF 200-400 f/4.