The light that passes through the clouds strikes the subject from many different angles. So on overcast day sunlight becomes a low-contrast light source.
The contrast of the light is not only one that influences contrast of a scene. We know that we can find high contrast in an image with low contrast
light and low contrast in high contrast light.
Contrast is also determined by subject matter composition,color in scene, exposure, and post processing. A scene that includes black and white subjects is likely to have more contrast than one with entirely gray objects.
but a software Levels or Curves adjustment can produce high contrast, even in an entirely gray scene in very-low-contrast lighting.
Increased and decreased exposure can reduce contrast in an average scene. However, increasing exposure will
increase contrast in a dark subject, whereas decreasing exposure may increase contrast in a light gray scene.
THE SIZE OF THE LIGHT
Selecting the size of the light is one of the most important steps in
a lighting setup. Time of day and weather determine the size of the light
A hard shadow often increases the illusion of depth more
than a soft one. When we understand this concept, we have another
way to manipulate the tonal values, and thus control the sense of depth,
in our pictures.
Diffusing screens, umbrellas, and bounce cards all increase the
effective size of any light. The effect of any of these is about the
same as that of another. Because all of these devices can produce
identical pictures, we pick the one that is most convenient. Thus, if
the subject is small, we are more likely to use a framed sheet of diffusion
material because we can place it close to the subject for
brighter illumination. It’s harder to construct a very large diffuser, so
we are more likely to bounce the light from a white ceiling to light a
Outdoors we can achieve the same effect by waiting for an overcast
day. Clouds make excellent diffusion material, effectively increasing
the size of the sunlight source.