What is the purpose of light in portrait photography?

We can see the external shape, structure and color of an object because it reflects light. Different attributes and directions of light help us to express the shape of the subject and create different picture effects.

Any object in the objective world has its special morphological structure, and the treatment of light is of great significance to the expression of the main form.

Sunward light is beneficial to show the shape of the light receiving surface, but the outline shape and three-dimensional sense of the object are relatively poor; Side light can form the light receiving surface, shadow surface and projection of the object surface, which is beneficial to express the shape and three-dimensional sense of the object; Side backlight and backlight are the best light to represent the outline of an object, while silhouette and semi-silhouette exclude the texture, structure, color and other information of the object, and are the most favorable forms to represent the shape.

Under the condition of scattered light illumination, if the object itself is bright and dark, and the color contrast is strong, it can better express the shape; If the contrast between light and shade and color of the subject itself is weak, it is difficult to express its shape; In the case of direct light, the dividing line between light and dark on the surface of an object is very clear, which can well represent its shape and outline.

We use light to express and shape the shape of objects. The treatment of light is of great significance to the expression of the main form. Different attributes and directions of light can produce different picture effects.

(B) the performance of the subject's spatial position

Objects in nature have three dimensions: length, width and height. However, photography displays objects on a two-dimensional screen. Therefore, in order to express the depth of an object, we must use the relationship between light and shade to express the three-dimensional shape and spatial perspective effect of the object.

We have all noticed this phenomenon in photography practice. Under the irradiation of light, the nearby scenery is relatively clear, while the distant scenery is relatively vague, dark, light, saturated and bright, and the distant scenery is relatively dark. This phenomenon of tonal perspective produces a sense of spatial depth of the picture. Under the side light and backlight illumination, the sense of space depth generated by this tone perspective will be stronger.

Under the illumination of side light and side backlight, the subject will cast obvious shadows, which can not only explain the approximate concept of the position, height or time of the light source, but also explain the spatial position of the subject. For example, when the sun shines at a low angle in the morning and evening, the projection of the object will be very long. The projection of an object can indirectly reflect the shape of the object, showing a spatial perspective, resulting in a picture effect of near darkness and far light, and can also show a strong sense of time by changing the number, size and length of the projection.

It is necessary to create a three-dimensional depth of a picture to represent an object in a three-dimensional space in a two-dimensional space such as a photographic picture. Present such a picture effect. There are many methods, and the air perspective effect formed by atmospheric dust is a common expression method.