Why use Flash?   To control contrast, freeze movement, not enough light, or to create a photograph:

1. Flash - can be used to freeze motion- Pan with slow shutter  speeds and use flash to freeze the motion in mid pan. Or use a slow shutter speed without flash to exaggerate motion. Pow Wow Dancerno flash

2. Control contrast - Contrast is the difference in brightness between highlights and shadows. Hi contrast - shadows are pure black - adds increased depth if desired.
Decrease contrast - by adding light to shadows with fill flash. Reduce the flash EV or output to minus 1 1/3 to minus 2. Some cameras will. do this automatically in the Program mode. Keep the dome diffuser off and the bounce card up to get catch lights in the eyes. _with fill lightwith fill light
3. Basic Flash Settings: Manual Flash, TTL-BL or TTL. Manual Flash: either Full, 1/4 power if >10 feet away from subject or 1/8 power if < 10 feet away.  TTL-BL to light background and subject - with aperture priority or Program mode - and matrix metering (or evaluative with Canon cameras - thus i-TTL for Nikon while e-TTL for Canon)
TTL to light just the subject (and control how the environment will look) with Camera on Manual and spot or center weighted metering.
4. Rear curtain sync (second curtain sync - Canon) - is best. It fires the flash at the end of the interval to produce the blur trailing behind the movement (instead of in front). For Blinkers - use front curtain sync or manual flash to turn off pre-flash. Mayor of Arthur Avenue
5. White Balance - Custom, Flash or Auto. Auto best if using flash intermittently during your shoot. CTO (color temperature orange) gel can be used to balance light or create a warming effect. Cowgirlwith CTO gelled flash
More about Flash next month.  E mail me your questions!