Citation:
Third-party lenses
The makers of third-party accessory lenses are not given this information when Canon
introduces new features or improves the performance of its cameras and lenses. It’s up to
them to continue to “reverse-engineer” their equipment to enable it to continue to work
on new EOS bodies as they’re developed. Since Canon designs our own processors and all
electronics within the body and lens, we have been able to maintain backward compatibility.
This is one of the many advantages of choosing a Canon EF lens.
When changes in communication result in a third-party lens that now produces errors,
it’s up to the makers of that lens to update the equipment to work on the EOS camera
in question. Again — Canon’s own EF lenses work without modification.
The meaning of “fully compatible”
Many third-party lenses with EF mounts are sold to customers with the claim by store
salespeople or even the lens manufacturer that they’re “fully compatible” with all Canon
EOS cameras. Canon, Inc. in Japan and Canon USA offer no rebuttal to those claims.
Any compatibility is based on the reverse-engineering we described earlier in this document.
And if a user mounts this lens on a certain Canon EOS camera and it locks up,
it’s up to the user to contact the lens manufacturer (after verifying it’s a lens issue; see
below) and tell the lens maker’s service department, “make it right.”
If a user encounters lock-ups
The easiest thing to do is remove the battery for a moment, and re-install it, which gives
the camera the chance to perform an internal electronic re-set. Try mounting a Canon
brand lens on the camera (even if it’s a dealer’s demo lens off the shelf) and fi re it to see
if you can repeat the problem. If lock-ups only occur with a third-party lens, it’s a
pretty safe bet that it’s the lens that must somehow be modified or adjusted. If, on
the other hand, the camera continues to lock up with a Canon-brand lens mounted, then
it’s likely that something else is wrong with the camera and it should be sent to a qualifi
ed repair technician or a Canon Factory Service Center for examination.
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