When would you use external flash? Flash power and Distance.

Do you need to meter the light if you use flash? It depends on the type of flash and light meter you are using. Some cameras and flashes have a TTL.

What does flash synchronization mean? Flash synchronization is the timing of the flash with the shutter of the camera. It determines the shutter speed you can use with a flash.

What does ETTL mean? Evaluative Through The Lens.

What will happen when you shoot faster than the camera sync speed? Black Bands Appear.

Why do photographers bounce the flash and use a diffuser? To soften the light.

What is a slave? it is used to instructs a flash unit to monitor incoming light.

What should you do if your image comes out too dark or too light? You can use the exposure compensation setting on your camera to correct for under or over exposure.