Flash Units in Digital Photography
Flash units can come in many sizes and shapes for digital photography. Those cameras on the lower end of the scale come with low energy built in flash units. However, some gear such as the high end digital SLR cameras can accommodate external flash units advanced in their abilities to provide excellent lighting in complicated situations. Know the basic facts about the difference between built in and external flash units.
In the early days of photography, flash units were much different indeed. They once consisted of powder that was lit by an electrical current and then literally “blown up” to produce a flash of light energy. This method was both dangerous for the photographer and difficult to manage as the flash units were not automatically designed to go off at the exact moment as the camera’s shutter. The task of ensuring the two went off together rested on the photographer.
The flash units of today are highly developed technology devices. The flash and camera are automatically synchronized using an electronic flash tube taking all of the pressure off of the photographer. Digital cameras today can determine themselves if a flash is necessary, can set their own intensity and other parameters and can trigger the flash at the precise tine the shutter is opened. All of this is done in the background with no manual effort. For those scenarios calling for a more hands on approach, digital cameras also include a manual mode where the user can set all of the same features to their specifications.
Flash units are separated into two basic categories: Internal built-in flash units or external flash units. Internal flash units are naturally built into the camera. Nearly all digital cameras come with such a unit and permit the user some control over it through the camera’s menus and buttons. External flash units are attached to the camera’s body through a dedicated slide-in slot or by using an electrical cable. Not all digital cameras can support external flash units. Generally the lower end pocket cameras do not support external flash units while all high end digital SLR cameras will. There can be quite a bit of difference in external flash units. They can have different light energy levels that they can emit and different mechanical characteristics. Some external flash units also include smart sensors to measure ambient light, distance and other optical parameters in order to make the most of the flash effect.
Digital cameras can use their flash units in automatic or in manual mode. In automatic mode the camera measures ambient light and fires the flash when not enough ambient light is available. Sometimes the camera will make the wrong decision as to using the flash and will either fire or not fire the flash when the opposite was needed. Setting the flash intensity is important too. If the flash unit fires too much light energy on objects that are too close to the camera the digital photo will be washed out. On the other hand if the flash unit fires a small amount of light energy on an object that is farther away from the digital camera the digital photo will be a too dark.
Your flash unit does come with boundaries. They can not light every object and every scene at every distance from the camera. Know what you camera’s flash unit limitations are. Experiment with different setups and determine what the highest light energy it can emit is and at what distance an object can be effectively lit from. This is called the effective flash range. Turn off the flash completely and use a tripod with a longer exposure if the object is out of the effective flash range. Should certain areas of what is considered a well lit scene still be dark, you might find it helpful to use the flash. This is known as fill-in flash and will fill-in the shadowed areas on objects in your photograph.