From
this article:
In
photography, the
golden hour (also known as
magic hour) is the first and last hour of
sunlight during the day when a specific photographic effect is achieved with the quality of the light during these hours.
Typically, lighting will be softer (more
diffuse) and
warm in
hue, and shadows will be quite pronounced as a result of the sun being so close to parallel with the horizon. This is because the sun light is traveling further through the atmosphere and coming from a less harsh side angle, instead of straight down. The golden hour is a mild version of
alpenglow, as described by
Galen Rowell.
During the golden hour, highlights are less likely to be
overexposed, because the direct light of the sun is less intense compared to the diffuse light of the sky. In
landscape photography, the warm color of the low sun is considered desirable to enhance the colours of the scene.
In the middle of the day, the bright overhead sun can create too-bright highlights and long, dark
shadows. The degree to which overexposure will occur will vary as different types of film and digital cameras have varying
dynamic ranges. This harsh lighting problem is particularly important in portrait photography, where a
fill flash is often necessary to balance lighting across the subject's face or body, filling in strong shadows that are considered undesirable. However, during the golden hour, such shadows are less pronounced.