- A flash unit consists of a tube filled with xenon gas, with electrodes on either end and a metal trigger plate at the middle of the tube.This is connected to a circuit including a small battery as the power supply.
- Low electrical current from the battery is converted to a high voltage current (couple hundred volts) by using transformers in the circuit (two inductors of coiled wire with varying number of loops).
- High voltage current is stored in two capacitors (large and small).
- When flash is fired, the energy in the small capacitor is applied as a high voltage pulse to the metal trigger plate in the middle of the xenon tube which causes the gas in the tube to ionize (negative electrons are freed from atoms).
- Ionization makes the gas conductive, and the big capacitor starts to discharge through the xenon gas.
- Negative electrons are attracted to the positively charged terminal. As they speed towards the terminal they collide with xenon atoms which become energised and produce light.
- When the large capacitor is empty (or is cut off in the case of manual power settings lower than full) the xenon gas stops conducting electricity and the light dies off.
Describe/define ‘electronic flash synchronisation’
Electronic flash synchronisation refers to the synchronisation of the flash to the shutter to ensure that the entire frame gets exposed to the light and the shutter does not block any part of the frame
during the flash burst. As the flash burst is very short the cameras shutter speed needs to be long enough to include a moment where the whole frame is exposed. This is also known as the camea's synchronisation speed.
Identify your camera’s synchronisation speed
Flash synchronization up to 1/320s (FP) adjustable with Built-in Speedlight or optional Speedlight (will reduce GN)
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