Flash Lighting in photography is used in situations when there is not enough of natural light. It consists of the main light, fill light and a background light.

Main Light

Main light is the strongest. It is set up first, 45 degrees away from the camera. The rest of the flash lights are subject to the main light. Main light defines:

    Size and shape of an object
    Color or mode (black and white photo)
    Persistence of shadows which play an important role in creating an impression of a dimension
    Shape and size of the bright surfaces
    Contrast of the shadows (strong, medium or soft shadow)

The right exposure is defined according to the main light.

Front Light or Fill light

Front light is set on the opposite side of the main light. It controls a shadow density. To reduce the strength of the shadows we use light reflectors.

Advisable is to make sure that the main and the fill light do not have the same intensity because in that case the object on the photograph will not have any shadows. Generally, that's not the desirable effect. (See High Key)

Contralight

It's used to accentuate hair. It also separates the model from its background and the object itself gets more of a volume to it.

Background Lighting

Sometimes it's necessary to light up the area behind the object. To do so we use a background light. If the object of interest and the background are the same color, background light can help highlight the shape of the object itself.

When setting up any kind of lighting (photo or video) it’s important to follow a few specific steps. First, set up the main light, then the fill light, and at the end, the background light. It’s done this way because if we would turn on all the lights at the same time, we would not be able to recognize which light is dropping which shadow. An affect like that is called a "stadium" effect.

When setting up the lights make sure to place them behind the camera to avoid its shadow falling on to the object of interest. The further the light is the weaker it gets and its strength falls each square distance so the exposure needs to be longer.

That means: If for one meter distance the exposure needs to be one second long then for twice longer distance the exposure should be four times longer, for three times longer distance the exposure should be nine times longer and so on..

Some advice / tips on Flash Lighting

As soon as you take the light further away, the contrast between dark and light area on the object gets stronger and the reflection smaller. As well as the contrast, the color intensity of the object becomes stronger too.

Although, there are set rules when it comes to setting up the lights, you don’t always have to stick to them.

In the first part I said the main light should be set up 45 degrees away from the camera and towards the object of interest, however, you can also set it up under a different angle and height depending on what kind of setup you prefer.

Main light can be any light of your choice, from a spot light and a flash light with a big softbox to the simple light ball. When it comes to flash lights there are different additions to it like umbrellas and softboxes.

However, when the umbrellas are better for shooting big groups of people because of its bigger light range, softboxes are better for single portrait shoots because of its better light control.

When shooting a portrait look out for the shadows around the nose. These shadows can lead to distortion and make the nose look quite longer or bigger, so as the outcome you can get a bad photograph. Tall look can mean being stuck up while innocent look can mean being humble.