Please help. I am struggling real hard to understand this photography game. I have a G6 and tomorrow I will be buying a used 420 EX flash. When this flash unit is attached to the hot shoe will it automatically overide the cameras built in flash or will they both fire together? Pathetic isn't it
Also are all 420 EX flash units compatible with the G series cameras as I saw an ad showing two types of 420 saying that only one was ok with selected G cameras and it was described as the 'new' 420 EX. Thanks in advance for any help.

