A quick note for you all – a reminder since I have said this before.
It is important, when using flash, to distinguish between the types of flash and their use. As follows:
 Flash is the only light.
- You want ambient light to be invisible
- So you use low ISO, small aperture and fast shutter
- You probably use manual flash and a light meter.
- E.g. in a studio you may use 100 ISO, f/8, 1/125th second
 Flash is the main light, but there is bright ambient light also.
Example: person in an office with a window behind him with a bright outsoors scene
- You want ambient light to look great – that may mean dimming it
- So you use manual mode (or exposure compensation, minus) to turn down the background until you are happy.
- Then, and only then, do you worry about (and turn on) the flash.
 Flash is the main light, but there is dark ambient light you’d like in the image
Example: A party indoors.
- You want ambient light to look great – meaning it should show!
- So you use high ISO, open aperture and slow shutter
- You probably use TTL flash
- Example: indoors party: 400-800 ISO, 1/30th second, f/4
 Flash is merely fill light
Example: Outdoors, a backlit subject
- You want the flash to not be too bright
- So you turn it down by using flash compensation, minus. Start at -1 to -2 stops.
A methodical approach works: once you realize what situation you are shooting, the rest follows simply and quickly. Failure to do this leads to much confusion. If you don’t know where you are going, you will not get there (paraphrasing Yogi Berra).