Understanding of light ratio of SLR photography

Because of the light, the picture will produce light and shade, layers, lines and tones. In the last article, we talked about the shooting effect of different light quality and light level.

What is light ratio?

Light ratio refers to the light reception ratio between the dark part and the bright part of the photographed scene in photography.

Under the irradiation of light, objects change in brightness. Due to different illumination angles of light, different distances between light sources and objects, and different textures of objects, different light and dark feelings will be produced. People can sum up the law of light and dark tones of objects as "three major faces and five major tones". (If you haven't heard of it, you can learn the basics of sketching. )

The three main surfaces are bright surface, gray surface and dark surface.

After being illuminated by light, objects show different shades. The illuminated side is called the bright side, the illuminated side is called the gray side, and the backlit side is called the dark side. This is three sides.

The five tones refer to: highlight, bright part, dividing line between light and shade, shadow and reflection.

Formation of light ratio-main light and auxiliary light

The formation of light ratio is mainly produced by main light and auxiliary light.

In portrait photography or still life photography, the main light is generally used as modeling light or side light, which can outline the shape and outline of the object.

The main function of auxiliary light is to improve the exposure of the dark parts in the picture, increase the levels and details of the dark parts, and reduce the light ratio between light and dark in the picture. When shooting on location, we often see a reflector as an auxiliary light source.

In a picture, there can only be one main light and multiple auxiliary lights.

Influence of light ratio on picture

Photographers introduce the concept of light ratio in order to better control the contrast of the picture. Different light acceptance rates of dark side and bright side produce different visual effects.

The light ratio affects the tone of our picture. If the light ratio is large, the contrast between light and shade of the subject is large, and the picture appears heavy, it is difficult to show the level and color of the subject, and the details and levels of the dark part will be lost.

When the light is small, there is little difference between the light and shade of the subject, the tone contrast is small, and the overall picture tends to be soft. Small light ratio is easy to show the level and color of the subject.

If you want to make people's skin color more natural and the picture softer when shooting portraits, you can use small light ratio to express it.

The greater the light ratio, the greater the tone contrast of the picture and the less details, which is usually reflected in the tonality of hard tones. The smaller the light ratio, the smaller the tone contrast of the picture and the more details, which is usually reflected in the tonality of soft tones or gray tones.