If you assign te AFL/AEL function to the red button in place of video and then go into the menu -> grinded wheel -> AF mode and set it to mode 3, it will AF on pressing the red button and lock exposure on half-pressing the shutter. You can also enable "AFL/AEL hold" and it will keep the focus at that point until you decide to change it.
Several people do that, I did it myself but now I switched back to mode 1 (half shutter press AFL, red button AEL) because I was dumb enough to forget to refocus...
|Dirt Hose by poppyjk|
|European bee-eaters by drvanger|
from A Big Year - birds
|Fat Is Beautiful Guinea 2008 DP by MarioSS|
from - Fat is Beautiful - (Woman's Portrait n Black and White+ A Border)