Canon 5D Mark II - Canon Lens Error 01 - Unable to Communicate with Lens

If you have suffered from Error 01 on your Canon lens, shown as a message on your camera as Unable to Communicate with Lens or similar then you may like to see what causes the error. This error is particular prone to occuring on the Canon 24-105 f4 EF lens and also on the Canon 17-85 EF-S lens.

These shots are of the internal iris mechanism that had failed on my Canon 24-105 f4 lens.

 

The point of failure is the cord that attaches the iris mechanism to the lens body. With the constant motion of the lens barrel for zooming and focus it can fracture or fray and the communication error Canon Error 01 is generated.

Canon Camera error 01 problem with 24-105 f4 lens

It doesn't even need a complete break in the cord to generate error 01 in your Canon lens, sometimes it can occur at certain points in the zoom range when the cord is either stretched or compressed more which causes the fracture to widen and break the communication link.

Photos of 24/105 lens with Canon error 01

Canon 24-105 lens error 01 Canon 5D2

Canon 5DII 24-105 lens Error 01

Last week I had a problem with my Canon 5DII and Canon 24-105 f4 IS L lens giving an Error 01 message, unable to communicate with camera. It appeared to be intermittent but as this is my workhorse lens that I use for almost every shoot I needed to get it fixed asap. The excellent Miles Whitehead repaired the lens for me and the fault was a known problem with the lens with the aperture unit connector failing. By losing contact at different points in the focal range it explained the intermittent nature of the error 01 fault on the camera.

This error occured on my Canon 5D too but showed itself in a different way; the error message on the Canon 5D2 was much more informative and showed the problem.

You can see the photos of the repaired part of the Canon 24-105mm f4 lens here

Canon 5D2 lens Error 01