Basic Flash Concepts

FLASH FACTS

• With every flash photograph there is two exposures in one

• there's an ambient exposure and a flash exposure

•  Fill flash can be used to eliminate silhouettes or shadows, when the subject is back lit or side lit

• flash exposure is not affected by shutter speed.

• the flash exposure and the range of the flash will be affected by the aperture and ISO settings

• the flash illumination is really affected by distance ( flash falloff) 

• the camera measures ambient light and flash illumination separately

• the flash illumination is measured after the shutter button is pressed and the flash output is adjusted, this is when you have automatic flash metering 

• Every SLR camera with a mechanical shutter box has a maximum flash sync shutter speed (this is important to know when you are trying to utilize a specific shutter speed to stop action) For Canon DSLR, 1/200 or 1/250

• you can eliminate harsh lighting, washed out subjects and red eye  using diffusers and light bouncing

•  it is possible to change the order of when the flash fires using "rear curtain sync"

• removing the flash from the top of the camera helps eliminate red eye and unflattering shadows