I am using a 70D with a 24-105L lens. When I switch the lens toggle switch from AF to MF, the camera still autofocuses. Have tried on One Shot, AI Focus and AI Servo modes but these make no difference - camera continues to autofocus. What am I not doing?? Or is there a fault that the camera is not reading the switch on the lens from AF to MF?
The switch should only disengage the focusing motor on the lens. The camera will still give focus confirmation for the shot you take. If the lens in MF and the motor is actively moving the focus in and out as you point the lens at object of various distances then it sounds like the switch is broken and stuck in AF. I would switch it back and forth firmly a few times and see if that helps, but if the switch is broke it will require service to fix.
It sounds like the switch on the lens could be faulty. Try a couple of fault finding techniques: 1: try a different lens on the camera, see if the AF/MF function is working properly. 2: if you have another body, or can borrow one, try the 24-105 lens on that body. If you use these fault finding techniques you will be able to see if the problem lies with the lens, or camera body.