Matt King,

Thanks for chiming in. "the right amount of flash that bounces back off the subject," learn something new every day.

So the aperture is the depth of field when using the flash unit just like without it. It's just the shutter speed is set to the side.

So the shutter speed is irrelevant and that is why it is set a 1/50s of a second. I wonder why they set it there, but that is going away from the topic if we tried to answer that.

The back of the flash does not give me the range of the flash but gives me the distance.

Matt, so my ISO is at 1600, I'm in a low light situation, I have the flash on TTL. The subject is 3.4 feet away from me -- yet the back of the flash stats f16, 23 feet. When I shoot the subject at 3.4 feet, I am wondering if it will give me a correct or right exposure of the subject.