Part 3: Understanding Lighting Contrast
Lighting size is the most important factor for lighting contrast, which in turn has an impact on tonal contrast, form and texture. Lighting size is pretty important and consequently requires a detailed discussion. The fact that lighting size does matter can be very easily checked by shining a flashlight at any object. The closer you move the light to the object, the bigger it gets with respect to the object, the softer the edges become in the shadow cast by the object. The softer shadow is the proof that lighting contrast has reduced.
Usually photographers learn to work with natural light before moving on to artificial light. The sun is the source of natural light. However big it may be, on a clear day it is a small source of light, just because it is so far away. On a clear day sun rays are travelling parallel casting sharp shadows. A sharp edge between lit and shadow areas is a characteristic of small source lighting. Highlights are small bright and hard. We get high lighting contrast.
Medium source lighting is the most desirable and most useful, generally speaking. When a cloud moves across the sun, the abrupt edge between light and shade that was the characteristic of small source lighting becomes softer. The window that lets in indirect light when it is bright outside is a also medium light source. A wall reflecting light into a shaded area is also a medium light source. We start getting more detail in highlights and shadow compared to small source lighting. Lighting contrast is less than that of small source lighting.
Large source lighting is shadow-less lighting. If you notice there is hardly any shadow on an overcast day. There is no distinct highlight. The same is true in shade in absence of any reflected light. Large source lighting has the least lighting contrast. As a result three dimensional aspect is lost. The image becomes flatter. If you have a busy scene to photograph and you feel the repetitive light and shade areas is cluttering the image, then the answer is to use to large lighting source. It will even out the light for photographing the busy scene.
The best way to learn about this key concept is to photograph the same thing under different lighting source sizes as shown in the picture above. Observe how the lighting contrast and tonal contrast changes and how detail changes across the tonal range. After that, try to see the affect of the same type of light source on different types of products.
This interaction between lighting size and different object is such an important aspect of photography that we will devote multiple posts to cover the topic.
