i have a canon xt.. i read that in evaluative flash metering that the camera compare the ambient light with the preflash .. now suppose that i am using manual creative mode and that i put my camera on f6 and 1/60 while the actual ambient metering is f8 1/8 seconds. this mean ambient underexposure.. so how the camera will act to compare the ambient and the preflash metering to give me a consistent exposure?...thanks.. need help

