Sunday, 14 September 2014

Fill in lighting - What is it? Definition, purpose, how to calculate its strength and how to determine correct light positions.

fill in lighting in architecture photography
fill in lighting in architecture photography. Photo: Jijo John

Definition of Fill in Lighting

By definition a fill in light is one that supplements the main light without changing its character.

What is the Purpose of Fill in Light?

The main function of fill in light is to brighten the shadow (darker) areas thereby reducing contrast in the scene.

What type of lights work best as fill in light?

Big, soft light sources work best.

How to get soft, diffused lighting indoors?

Artificial light sources like flashes and strobes are by their very nature hard light sources, but one can easily modify the light coming from them by simply bouncing it off walls or ceilings, using light modifiers like umbrellas, softboxes, diffusion panels, scrims etc.

How to calculate the strength of the fill light for any given situation?

As we have discussed in our previous article Deciding Lighting Setup for Interior Photography Based on Client Requirements, the strength of fill light should be decided by answering two fundamental questions, what do I need to show and how do I show it?

For most architectural photography work the ratio of key light (read ambient light (daylight streaming in through doors and windows + light coming from light fixtures in the room) to fill light will be 1:4. The available light is used as the primary source of illumination and supplemental flash/strobe light is added to the scene the power of which will be at least 1 ½ - 2 stops lower than the key.

How to decide best light positions?

As we are dealing with soft, diffused light sources, the precise placement or angle is not important. It could either be placed behind the camera, at an angle between the camera and the dominant light source in the scene (closer to the camera or even at the opposite side of the camera to the light source). Care should be taken to ensure that the fill light only reduces the contrast in the scene, the gradual transition from light to shade should be maintained and also it should not cast additional shadows. 

When done right the interior photograph gives the viewer the impression that no additional lights were used to photograph the scene.

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