# Patent: Dedicated RF-EF adapters for Canon Big White Lenses



## InchMetric (Feb 7, 2022)

The US Patent and Trademark Office has granted patent 11,212,451 for a lens adapter that is effectively a dedicated adapter. The patent is not limited to Canon lenses, but was inspired by the Canon transition to RF from EF lenses, and particularly the potential desire for an unadapted look and feel on super-telephotos that avoids the risk of inadvertently decoupling the lens from the adapter. 

The patent covers the particular feature of the latch that engages the adapter to the lens being "inoperable" when the lens and adapter are mounted on a camera body. The latch may be internal to the adapter, or if external, recessed, smooth or otherwise intentionally difficult to inadvertently actuate. There may be an interlock to prevent a normal latch from actuation which connected to a body.

The inventor is a patent attorney specializing in optics, who has a number of other camera patents to his name. "_Like with most patents, my inventions are simply novel solutions to problems that I have encountered. In this case, I was resistant to buy a new $12,000 lens of an old format and have it forever mounted with an adapter that didn't feel like a proper solution. Since then, Canon has decided to release the RF 400 f2.8 alongside the EF 400 f2.8iii, so this invention may never be needed. But I imagined them producing the RF version with a dedicated detachable adapter that EF owners could easily remove, and this invention was intended to help solve that problem_."

The invention is available for licensing.


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