Quality of Light
When speaking about the quality of any particular light, we usually talk in terms of "hard light"—which usually is coming from a small, single spot or source—and "soft light," which is more diffuse and seems to come from multiple directions.
Examples of hard light might be the sun, which is a small light source that creates hard light and shadows, or a flash that is pointed directly at your subject without passing through any diffusion material. Hard light is usually very directional and, due to this fact, the shadows that are created by it are very hard-edged. Another characteristic of hard light is that there are very few midtone values separating the highlights from the shadows (Figure 4.8).
Figure 4.8 Mid-day sun is a perfect example of hard, directional light that creates dark shadows and lots of contrast.
An overcast day is a perfect example of soft light, where the sun has to penetrate through a cloud layer. The cloud is spreading the light, making it come from multiple angles instead of a small, single point. This is also called diffusion; the light spreads out and creates much softer shadows. (It may actually appear to eliminate shadows altogether.) It also helps to create much more defined midtones because there is a smoother transition from the bright to dark areas (Figure 4.9).
Figure 4.9 An overcast sky creates a soft, multi-directional light that creates a lot of smooth tones and no hard-edged shadows.