For most of us firing the flash is something that happens in the background and that does not require our attention.. Flash photography was not always so easy to use. Flash is useful in many situations for example when taking photos in dark scenes or when getting rid of shades in fill in mode. It is beneficial to know some facts about flash usage and how it works.

Flash photography has been around for more than a hundred years. At first it was a dangerous and a manually controlled technology. It used powder that was literally ignited by either fire or electrical current. These flash solutions were both dangerous and hard to use since the flash was not automatically synchronized to the camera's shutter. This meant that the photographer had to manually synchronize the shutter and the flash making sure that the flash was fired at exactly the time when the shutter was being opened. Modern flash units use an electronic flash tube that is synchronized to the camera's shutterrelieving the photographer from the burden of timing the shutter and the flash.

Here are some facts that are important to know about flash units and shooting photos using them:

Internal flash units: Internal flash units are built into the camera. They are controlled through the camera's menus and buttons. Internal flash units are usually small (limited by the camera size). As a result they are relatively weak units and only allow photography in dark conditions to a distance of a few feet. Internal flash units are easiest to use as they do not require any special settings or buying and installing accessories. In most cameras the internal flash can set to an automatic "point and shoot" mode in which the camera fires the flash whenever it senses that it is needed. Some low-end cameras can only use built-in flash units. Most cameras however support external flash units attached to the camera body.

External flash units: External flash units are either mechanically attached to the camera's body through a dedicated slide-in slot or are mechanically detached from the camera and only connected via an electrical synchronization cable. External flash units come in many sizes and have different features. They vary in intensity?C how much light they generate and for how longand in mechanical featurescan they be tilted or skewed or are they fixed in relation to the camera's body. The external units are electrically connected to the camera allowing the camera to control the flash timing. Some connection standards also transmit advanced information to the flash unit such as the reading of the camera's light sensors, its optical settings and more. This allows smart external flash units to optimize their settings for shooting the best photo.

Firing the flash:The decision to fire the flash is either automatic or manual. The camera can fire the flash when there is not enough light available. In some scenarios the camera will not automatically fire the flash although doing so would have resulted in a much better photo. One such scenario is taking a photo during day time when the object is shadowed. For example if the object is wearing a hat the hat can block the light from the object's face or when the object is lit from the side the object's nose can block the light creating a shadow. In such scenarios the flash unit can be set to "fill in" mode. The flash will be fired to fill-in those shadowed areas but it will not be fired strong enough to wash out the photo. Another scenario is when the sun is behind the object. One example is taking a photo on the beach during a sunset. If taken without a fill-in flash the result will most likely be a silhouette of the object. If taken with a fill-in flash and the object in range the result will be a clear photo of the object against a sunset.

Flash can also cause problems: Shooting a photo using the flash can also cause problems. One such problem is washed out photos as a result of the flash being too strong or the object too close to the camera. Washed out photos do not have enough details and the object appears to be too white or too bright. Another problem is a photo with more details than in the original scene: in some scenarios the flash can create artificial shadows and lights which result in a photo that includes details that are exaggerated relative to their appearance in real life. For example when taking a photo of an older man using a flash the skin wrinkles and imperfections can look much worse than they really are in real life.

Flash is limited: It is important to know the limitations of the flash unit. Any flash unit has a certain amount of light that it can generate. Usually this amount can be translated to an effective flash range. When trying to take a photo with the object too farmore than the flash unit rangethe object will appear dark. If you need to take a photo with your objects not within your flash unit range it is better to turn off the flash completely and use a tripod and long exposure. Using the flash in such scenarios can fool the camera into setting lower exposure which results in a photo darker than a photo taken without using the flash at all.

It is important to know the flash unit that you are using and to get a feeling of when and how it should be used. The best way to accomplish that is by experimenting. With digital photography experimenting is practically free as there is no film development costtake advantage of that and experiment shooting photos in different scenarios with and without a flash.