Come over to the Dark Side

Flash Photography - This image uses a flash which has been taken off
the camera to show nice highlights. 

Sometimes photographers encounter situations that have insufficient or unworkable existing light sources. Maybe the shadows from a tree keep on going on a person's face. A flash can be used to eliminate these variables.

Today's flash is termed as an electronic flash. But it's in the origins of flash photography that a powder flash was commonly used.

In the 1930s the more simple and safe flashbulbs were developed to replaced the powder. Later the flashbulbs were replaced with electronic flashes.

"Press photography was in the transition era between flash powder and flash bulbs. …I rigged up my Korelle with a rudimentary flashgun. With tinfoil wound around the finger release button to make contact and a table lamp reflector mounted onto a flashlight to utilize No. 5 flash bulbs."

Flashes are a type of light defined as a 'momentary' light source. As opposed to a 'constant' light source such as daylight or tungsten.

All flash units are not created equal. Some are considerably more powerful than others, and this power is expressed as a guide number. The GN is determined by the maximum distance multiplied by the aperture (rounded off) for a given ISO.

The GN of a professional flash unit is 45-60. A GN of 32 @ 100ISO would have a working distance of 4m when providing f8 worth of light (f8 x 4 = 32)

Flash light is a burst of light, for a very short time. Because there is no time over which light can react with the film as with a constant light source.

The exposure of the flash is only controlled by the aperture.

ETTL - Electronic through the Lense - Is a function on a flash that works out most of the settings for your flash.

The automatic controls allow you to set the amount of light required, as long as you are working within the maximum allowable distance (GN formula)

The numbers on these settings correspond to the aperture ring and are THE AMOUNT OF LIGHT NEEDED TO EXPOSE THE FILM THROUGH THAT APERTURE.

As far as a shutter speed is concerned, electronic flash is synchronized to fire when the shutter is fully open because the flash reaches its peak brillance almost immediately and has a very brief duration.

So how do we expose with a Flash...? 


What happens when you want both available light and flash exposed together? You mix the flash with the available light.

The burst of light can freeze motion especially in nighttime shots.