Small Flash, Big Light
For the scope of this class, we'll just be talking about small flashes, the kind of flashes that are built into your camera or that you can add as an accessory to the "hot shoe" on top of the camera.
The larger, camera-top accessory flash units are commonly called "speedlights."
What's In Your Flash?
These flashes are composed of basically three components; a battery, a Xenon flash tube, and electronics that boost the voltage, store it, and control the release of that energy as light. The voltage of this current from around six volts to hundreds and sometimes thousands of volts.
This high voltage is stored in capacitors, which are capable of releasing all of that voltage instantaneously. This is what's happening in the charging phase of your flash. Depending on your battery freshness and the amount of lighting power you need, this charging phase can take anywhere from a fraction of a second to several seconds.
Many flashes make a high pitched noise while charging, and some even beep when they're ready or have a light that goes on or off. Once your flash lets you know that it's ready, it means the capacitors are full and can deliver that incredible amount of power over an extremely short amount of time.
Working With Artificial Light
We're talking fast; about thousandths of a second. This is what makes flash photography so amazing: a pocket sized flash with four AA batteries is capable of producing light that can compete with the brightness of the sun.
The other thing that makes flash awesome is that because of the extremely short duration of the light, you can freeze action, and usually you can freeze it even better than a really fast shutter speed. In fact, most of the really cool high speed photography that you see is done using high-speed flashes and relatively slow shutter speeds.
If you wanted to do the same thing with constant lights, you would need a truck to carry the lights and the generators to power them.
So as you can see these flashes take advantage of quite a bit of technology to pack a powerful light into a very small package. And this is the reason I love using speedlights.
In our next lesson, we're going to be learning how to break down light from your flash into four distinct and controllable components, and this will simplify the process of getting exactly the light you want.