Originally Posted by Mallee Boy 
G'day Kenyee,
Go to your custom menu......scroll through until you find "catch in focus"...which will be set to 'OFF' by default....activate it, ...and away you go.
Cheers
The "catch in focus " option doesn't disable the AF double check, it just allows you to prefocus at a given spot with an AF lens set to MF (if the AF lens has a AF/MF selector) and let the camera take the shot when focus is achieved.
On earlier models, this was only feasible with MF lenses.