What is incident light?
When light falls on a subject, whether it is directly or indirectly it is called incident light. Direct sources of incident illumination are sources that emit light like the sun or a strobe unit aimed at the subject. Indirect sources of incident illumination redirect light onto the subject. Maybe a wall can be used from which sunlight bounces back onto the subject or a reflector that redirects light from a strobe onto the subject. In both cases, the light can be metered and controlled.
What are the important aspects of incident light?
The major aspects of incident light are:-
Intensity- is the amount of light that illuminates the subject, directly from a light source or indirectly from secondary sources of reflected illumination. The intensity can be metered and controlled with the help of light modifying techniques.
Hard vs Soft-when the light is hard there are sharper shadow edges during the transfer between highlight and shadow area, the shadows are sharp more dramatic and accentuate form and texture. Whereas soft light cast a broader shadow edge more gentle and smooth forms and textures. Mostly found in portraits.
Size and distance-the smaller and closer the light source, the sharper and harder the light. The larger and farther the light source, the softer and lighter is the light.
Direction- the direction from which the light falls or the direction from the picture/video is shot also plays a major role in capturing a picture.
Contrast- the difference between the brightness and the highlight and shadow areas of the photograph.