Seeing The Light

HTML clipboard The purpose of this lesson is to provide a simple demonstration of how the photo of a subject is affected by the position of the light source. The camera does not "see" exactly the same way we do. Not only do our eyes adapt to the ambient light, our perception evens out the lighter and darker zones in a scene to some extent. This is not the case with a camera. When the light source is directly above and behind the camera its monocular view flattens out the subject. Therefore, the angle at which the light strikes it is important to bring out relief and depth, and in turn the combination of shadow and light will impact the mood of the image.

HTML clipboard Any source of light can be visualized as originating from a point within a hemisphere surrounding the subject. Depending on the shape of the subject, the camera's vantage point, and the point of origin for the source of light, the image will change dramatically. In outdoor photography, this entails an awareness of how the sun's light strikes the subject. On a very sunny day shadows will be harsh; on a cloudy day the shadows will be softer and the light more diffuse. 

HTML clipboardThe series of photos below illustrates the point. In these photos the light source is artificial, but the principle would be the same if the source of light were the sun at different times through the day.
 
 In these photos, the camera's position is fixed and so is the subject. Only the position of the light changes. The small graphic below each photo indicates the point of origin for the light: 

HTML clipboard In photo #1 the source of light is nearly overhead and in front of the subject. Note how the face shows little shadow and how the image appears to have little depth.
 
In photo #2 the source of light is slightly lower and a bit to the side. Now ,one side of the face has greater shadow and more depth. 

HTML clipboard With photo #3 the source of light is nearly directly overhead. This is similar to a noon sun. In this image the eyebrow ridges are highlighted and the eyes are in shadow. Notice the arms and elbows are so deeply shadowed as to be featureless.
 
In photo #4 the source of light has now passed slightly behind the subject, and some of the light is reflected from the ground. Although the subject is mostly in the shadow, the light still catches the most salient features.
 

HTML clipboard In photo #5 the subject is now fully backlit and the subject is a silhouette. Few of the details can be seen, although the subject can still be identified.
 
Finally, photo #6 has a source of light tat is low and off to the side, creating an effect much like late day sunlight. The low light emphasizes the contours and relief of the subject.
 
 As can be seen, the changing angle of the light source has a dramatic effect on the way the camera records the image. However, it is not the only factor that affects the contrast and shadows in a photo. The other factor is generally referred to as the "quality" of the light.
 
The quality of the light refers to its harshness or softness. Very bright direct light is considered harsh. Harsh light exaggerates minute details, and produces deeper shadows. That quality of light is ideal to bring out textures. Soft light is diffuse light, such as sunlight filtered by clouds. Soft light tends to decrease detail, and smooth out textures. If the light is diffuse enough, then shadows can almost completely disappear and images may have minimal contrast.