I have a 40D and am interested in getting a remote/cable shutter release. I have only seen the cable type on some DSLR's that physically connect to the camera. I have heard that there are remote controls that do the same thing. That would be preferrable. I have a 100-400 coming and heard to test it properly to be sure it is not a "soft" lens, I need to use a shutter release and engage the mirror lock. It would be an accessory I would want for other uses as well but now sounds like a good time to buy it. What do you suggest?