Will Canon allow EF lenses to work on future RF bodies?

Robert Krawitz wrote:

Sittatunga wrote:

In the past Canon were still trying to sell FL lenses after they brought out FD and FD lenses and cameras after they brought out EF. It's the market that has killed off Canon's previous product lines long before Canon wanted to, and I don't think that's changing now.

Canon had technical reasons for the FD-to-EF flag day. The FD mount diameter was small,

48mm diameter clearance, 42mm flange distance compares with 51mm diameter clearance for EF and RF at 42/20mm flange distance.  And just over 43mm for EF-M. The big problem was the overcomplicated New FD kludge that gave them a lens release button like everybody else (but positioned to been you fingernails on the mirror box) at the expense of being able to put electrical contacts within the lens mount. Screwdriver AF would have been impossibly complex too.

making it more difficult to design very fast lenses, and it was purely mechanical. Canon decided to go with a fully electronic mount with no mechanical aperture or AF coupling, and FD lenses obviously couldn't be retrofitted with electronics. FD was before my time -- I got my first SLR in 1995, a Rebel XS -- but I think they made the right decision to bite the bullet and get the EF mount right. They added a few things over the years, but with no compatibility issues (well, except for one early low-end lens with no manual focus and one early body with no AF

that was the EF-M, designed to keep faith with the (very few) people unconvinced by AF.

), and they had no trouble keeping it going strong ever since.

The EF-RF adaptors don't look like a pro forma stopgap. There are no fewer than three of them, with varying features. Having an RF-style control ring on the adaptor makes EF lenses in some ways more useful than RF lenses that lack the control ring.

And the filter adapter is wonderful for those lenses that have huge filter threads or won't take front mounted filters.

Nikon stuck with the F mount, and retained the mechanical aperture coupling and added a screwdriver AF mechanism. That allowed older AI-S lenses to keep working...well, until they needed electronic coupling after all, and then there eventually was a crazy quilt matrix of some lenses working with some bodies but not others (in both directions). Screwdriver AF mechanisms are very slow and noisy, to boot.

They also don't AF when adapted to Z mount.

The basic mount remained the same, so it may have been physically possible to mount an old AI lens on a digital body, but it wouldn't have been very useful.

The M mount really didn't look to me to be a path forward. It's very small diameter, they never built higher end bodies or lenses, and Canon never looked to be taking it very seriously. RF is something very different.

Canon said at the launch that the M mount was optimised for APS-C and, up to the time they introduced the R with its crop format 4k video, avoided making their crop format lenses compatible with full-frame cameras. With hindsight this was hubris and possibly a mistake, but it saved them from complaints from people putting crop lenses on film cameras.