Mounting Canon FDn lens to Sony a7R NEX adapter

Here is a quick post about mounting Canon FDn camera lenses to a Sony a7 a7R NEX e-mount adapter. The adapter being used is one of the cheap Fotasy units from overseas. Some of these NEX adapters have different labels on the adapter ring, for example, “lock” versus “close”, but the functionality is generally similar. Fotodiox is another lens adapter vendor.

The rotating rings on these cheap Canon FD/FDn adapters don’t necessarily lock the lens to the adapter flange, the lock function is actually done by the lock ring on the lens itself. For FDn lenses, there is a button on the lens ring that you have to push, before the lens can be rotated off of the adapter flange mount.

If you are new to Canon FD/FDn lenses, the first thing to know is that with an un-mounted FD/FDn lens, you can’t always control the lens aperture by rotating the aperture ring on the lens. The lens has to be mounted first, which is not usually the case with camera lenses manufactured by other companies, like Pentax, Nikon, etc. So if you are evaluating a Canon FD/FDn lens for purchase, for instance, be sure and at least take one of these cheap adapters with you, so that you can confirm the condition and operation of the aperture blades. The blades need to be free of oil, and they need to move easily.

The second thing to look out for is to make sure that the lens pin is engaged properly on the Sony a7R NEX e-mount adapter. With the cheap adapter shown below, the lens can be mounted with the pin on the wrong side of the actuator lever in the adapter, which means that the blades won’t move when you turn the aperture ring on the lens.


Dan Euritt

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