Diffusion: Controlling Contrast

In the field of photography, light diffusion is one of the basic skills that photographers need to learn and master. It involves softening the light that hits the subject. Controlling the amount and type of light that reaches the subject affects the highlights, shadows and range of tones on the image. Through the use of a soft box and layers of lighting diffusion materials, photographers will be able to control the light ratio and improve how the final photo will appear.

The Soft Box as a Source of Hard Light

A soft box is a device used to provide additional light to the subject. It is made up of three main parts: the box or enclosure, the baffle and the diffusion layer. The enclosure contains a bulb surrounded by a reflective material. Attached to the opening of the box are the baffle and diffusion face. These two layers help soften the light around the subject, creating a wrap around effect. Without the baffle and diffusion face, the light appears “hard.” The hard light produces a high contrast between the light and dark areas. When taking a photograph of a highly reflective material, the interior of the soft box may also be reflected on the material.

Attaching the Baffle

The baffle is the first level of diffusion on the soft box. As the amount of light that passes through is reduced, it may be necessary to compensate for the exposure by changing some of the settings on the camera. Taking a photo of the same subject, the photographer will notice that there is some improvement on the quality of the image. A reduced contrast ratio will make the highlights look cleaner and more level. Shadows will appear softer while the light will start to have a wrapping effect on the subject. Although the contrast ratio is reduced, the range of contrast between the light and dark areas is still great. Any detail on the reflective material may fade or appear indistinguishable.

Installing the Diffusion Face

By attaching the diffusion face, the light will appear much softer once it passes through the layers. As the amount of light is further reduced, photographers will need to adjust the exposure to compensate. The light appears to wrap around the subject even more because of the diffused effect. As the light becomes more diffused, the contrast range is reduced, making the highlights and shadows appear more uniform. Intricate details engraved on reflective materials become clearer.

Adding Diffusion Layers

Essentially, by adding more layers of light diffusers, the light becomes softer. The highlights, shadows and details become closer to their true value. Additional layers can be added by attaching them on Main and T-clamps. When arranging the soft box and light diffusers, it is important to place them slightly below the lower edge of the subject to evenly illuminate the entire scene, unless a different effect is desired. It is important to note that for each additional diffuser attached to the soft box, the amount of light is reduced, requiring additional adjustments on the camera settings.