The 430EX II's AF-assist beam is compatible with the AF points of almost all EOS cameras. The AF- assist beam is compatible with 28 mm and longer lenses. The effective range is shown below
Custom Function Settings C.Fn-02-113: Convenient when you want to use the depth-of-field preview button to check the depth of field. C.Fn-08: If the Speedlite or camera's AF- assist beam is disabled, the AF- assist beam will not be emitted.