In photography, be it digital or analogue, light is everything. Not only
is light what the camera captures, the angle at which light falls on
the subject in relation to the position of the camera dramatically changes
the way the image looks.
The purpose of this article 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.
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.
The 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:
1
2
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.
Moving the source of light higher to the side and above alters the image
further. This is the case in photos #3 and #4 below which
could be compared to photos taken under a midday sun.
3
4
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.
In the last 2 images the source of light is low.
5
6
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.
