Canon m42 to eos adapter generates error

oldgearuser · Joined: 15 Oct 2023 Posts: 5 Location: uk

Fix for Canon m42 to eos adapters error code when trying to take a picture.

On my 1Ds mk2 when using an m42 to eos adapter without eos chip, the mirror locks up, the shutter opens, and the error 01 appears on the display. Switching the camera off and on again clears the error and resets the camera, no harm done but no picture can be taken.

This only happens on some Canon eos cameras, my 1DS mk 2 suffers this I believe other models suffer it as well.

It is not a camera or lens fault it is a feature and can be easily overcome.

There is a switch hidden under the lens throat flange on the camera. The reason for this switch is to tell the camera that an eos lens has been fitted and the camera can then communicate with it.

An adapter without a chip cannot communicate with the camera so it generates a failure to communicate with lens error code 01 and locks up the camera.

An adapter with a chip present communicates with the camera so it does not generate the error and it does not lock up the camera. Of course the chip gives the camera wrong lens information but that is irrelevant for general operation.

Drilling a second hole in the correct position in the adapter without a chip, stops the adapter from rotating far enough to trip the switch, so the camera thinks there is no lens fitted and it then functions normally.

Full manual exposure control functions, and aperture priority automatic exposure works normally as well. In other words the camera functions normally for these two modes.

The distance on my unchipped adapter that I chose for positioning the new second hole is 7mm in advance of the existing hole or approximately 23mm from the red dot.

Drilling the new hole is a permanent fix on an unchipped adapter.

I cannot say if the switch is in the exact same position on every model, it is quite likely to be in the same position in the camera lens throat however.

Not every Canon camera has this switch, only apply this fix if your camera suffers the issue. Or simply acquire a second adapter fitted with a chip to avoid having to drill the adapter.

Good luck

paulhenge · Joined: 03 Nov 2023 Posts: 1

All cameras encounter this situation, but the frequency is extremely rare. Purchasing a second adapter with a chip to avoid having to drill the adapter is a preventative solution that should be considered bad ice cream