I just wanted to let you all in on a little tip that I found with the Mark III and how it is capable of making your life a whole lot easier.
If you know about it then good for you. If you don't then try it out...
This is primarily for the photographers who like to assign the '*' button for their auto focusing over those who just press the shutter half way.
The feature that helps me get the shot 10/10 times is that I have my AF set to the AF-ON button on the back right and I have the * set to a registered camera setting. I move my thumb to the * when I don't have time to adjust my manual settings so it just jumps into Av mode with +1/3 EC so I can always get the shot and get it exposed in the ballpark. As soon as I release it it back to normal Manual mode. The * button also does the AF as long as going into Av mode.
I have my Mark III set up as follows:
cFn. IV - 1: Shutter Button/AF-ON button = Set this up with what you do in mind. The main thing here is to assign the AF-ON button to do all the Autofocus action. I don't have my camera near but I think I am set to 0 or 3. Who knows.
cFn I - 14: Apply Shooting/Metering Mode = Enable. I registered this to put me into Av mode with + 1/3 exposure compensation. This means that every time I press the * button, my camera will not only auto focus, but it will also jump into Av mode with +1/3 exposure compensation. No need to fidget with my settings. All I need to do is move my thumb from the AF-On button to the * and I am in Av mode to ensure that I get the shot. You can assign this button to whatevr you want really. Program mode, Tv mode whatever!
cFn. IV - 2: AF-ON/AE Lock Button Switch = enable to switch their functions so you are back to AF with the * and the AF-ON will activate the registered camera setting.
This is open to interpretation and isn't perfect for everyone. If you think it would be helpful then give it a shot and let me know what you think.