My 24 1.4L basically doesnt focus at times. It usually beeps but the red focus confirmation light doesnt blink (on both my 7ds) I have no idea why it happens. I would have sent it to Canon but unfortunately we don't have the Canon service center here so it has to be sent to another country which usually takes 1-2 months, butt load of $$$ and (in a lot of cases) the problem(s) still aren't fixed.
