What is the function of light in photography? Please answer in detail and be professional. Thank you! Please tell me.

The function of light in photography. Photographic light processing refers to the photographer's use of light to shape characters or scenery images according to the requirements of the theme (or content) of the work, in order to achieve the artistic effect required by the content of the work, that is, to complete the task of modeling and express the appearance and ideographic task such as dramatic atmosphere. The role of light in photography creation is manifested in three aspects: (1) illumination, that is, illuminating the subject; (2) Modeling function, that is, expressing the external form of the subject, including three-dimensional texture and tone expression and external contour. (3) Ideographic function, that is, light is one of the important ways of photography. The functions of these three aspects are progressive in turn, which is also a way to understand what a good photographic work is from the perspective of light. Specifically, a good photographic work can not only make people see what they are shooting, but also make people truly feel the objective existence of the subject. It can not only make people feel the objective existence of the subject, but also make people understand and appreciate the thoughts and emotions conveyed by the subject through the picture. A good photographic work should not only attract people in the picture, but also impress people in thought and emotion, which is impossible without the shaping of light. The photosensitive material used in photography can only play its due role through the light source. In photography, light is not only used to illuminate objects, but also to convey information of objects. In this respect, it plays the role of a bridge and a medium. For example, the shape, volume, quantity, color, texture, spatial depth and other information of the subject, as well as the bright and dark configuration of the subject's tone, picture atmosphere, hierarchy and many other aspects, must be expressed through the effect of light. Therefore, the photographer can't simply observe the light from the surface image, but should use the light flexibly in practical conception. In a subject, different illumination angles and illuminance will produce different effects. However. We must master the effect and sense of light in photography, be good at using it and have a keen sense, which is the instinct of photographers. Painters draw objects with skilled brushes in their hands, and photography expresses objects by using light. So light is the soul of photography, and it is necessary to complete the process of photography. Expressing the essence of photography depends on light. Only by correctly understanding the changing law of light, understanding its artistic effect and making full use of it in photographic art creation can we love light as gold and use it as a god. 2. The expressive force of light in photographic art modeling. Photography is a plastic art, and light plays a key role in the expressive force of photographic art modeling. In photography creation, we should have the consciousness of light modeling and mobilize the means of light modeling to achieve its artistic effect. In photography, the reproduction of objects in the picture depends on light as the medium of communication, and light is of great significance to the modeling performance of photography, the rendering of environmental atmosphere and the expression of thoughts and feelings. In nature, light is ever-changing, complex and subtle. During the day, with the change of time, the direction, angle and intensity of sunlight are constantly changing, which will bring different effects in photography modeling. For example, the sun will rise or fall to 15 degrees, that is, in the morning or at night. It is characterized by small incident angle of the sun, large light receiving area on the vertical plane of the scene, long projection of the object, large contrast between the light receiving surface and the shadow surface, small light intensity and softness. In this light condition, it is easy to get a clear sense of air perspective by shooting with backlight and side backlight, and the picture presents a strong atmosphere and poetic modeling effect. When the illumination between the sun and the ground is 20-60 degrees, this kind of light is characterized by moderate incident angle, clear light direction, small brightness change, good modeling effect, slow light and shadow movement and moderate color temperature. This is the prime time for photography. At this time, the shooting scene is clear, the color tone is clear, and the layers are rich, which is conducive to the three-dimensional sense, space sense and texture of the scene in modeling. At this time, choose different directions of light modeling, so that the scene can obtain the effect of clear tone, rich layers, rigid lines and bright light. When the illuminance is 70-90 degrees, the sun shines vertically at noon, and the object can only receive more light at the top and less light at the vertical plane, which makes the illumination contrast of the scene large, lack of hierarchy, poor perspective effect and lack of stereoscopic effect. Therefore, this kind of dome light is rarely used in photographic modeling effect. Judging from the change of direct sunlight in a day, the influence on modeling is different, so we can choose the direction of illumination to design modeling.

. According to the direction of shooting illumination and the direction of the sun shining on the object, the direction of illumination is basically divided into forward illumination, lateral illumination and reverse illumination. The difference of these three kinds of lights has also produced different effects and influences in photographic modeling. The expressive force of smooth light on photographic modeling makes the light-receiving surface of the object balanced and can fully express the texture of the object. The timbre configuration is mainly completed by the timbre of the object itself. However, daylight lighting is generally not conducive to the expression of the spatial sense and three-dimensional sense of objects, with dull and monotonous tone and weak sense of hierarchy, lacking the visual rhythm effect of scientists' ups and downs, and is not suitable for the expression of scenery modeling with large spatial sense and a large number of objects. Side light has a strong expressive force on photographic modeling, which can make the light-receiving surface and light-dark surface of the object clearly appear, the light-dark configuration and contrast of the picture are clear, the layering of the object is rich, and the aerial perspective phenomenon is obvious, which is conducive to expressing the spatial depth and three-dimensional sense of the object. It is an ideal light source for photographic modeling effect. However, when using it, we should pay attention to the proportion of light receiving surface and light and dark in the picture modeling. Backlight can show the contrast between spatial depth and ambient atmosphere, show the effect of spatial perspective, and help draw the outline lines of objects and show the number of objects. It is better to use low-key pictures to express the artistic effect of object modeling, but remember to use dark background to contrast the main body. When shooting a close-up or close-up, it is best to use the supplementary light method to make the texture of the front of the object better, and the exposure is mainly positive brightness, so that the modeling effect is better. It is the only way for photographers to correctly understand light, master the changing law of light and understand the expressive force of light on photographic art modeling. British photographer Keane? Nelson believes that photographers should discover and study the different changes of light in a day and a year, and understand its full significance. He put forward a method to observe the effect of light change: find a local scene and take it on a sunny day, one every hour. If you shoot from one position, you can see the changing effect of light when the sun moves. You can also shoot around a theme at a certain time of the day, and you will be surprised by the various lighting effects you get. If you want to know how strong the sun is, you can also try to take the sun into the picture, but be careful not to let the strong light hurt your eyes. After 3 pm or before 9 am, you can take a silhouette photo in the sun. You can move the lens away from the sun first, so as to measure the exposure reading; Then, according to this reading method, all the scenes including the sun are photographed. Then, change the aperture and take another picture as it is. After the film is developed, compare the final effect. 3. The color reduction elements of light play a direct role in correct color reduction in color photography. There is a close internal relationship between light and color. Generally speaking, color comes from light and changes with light. There is a simple reason. People can clearly distinguish the color of an object in light. If there is no light in the dark, it is difficult to distinguish any color, because colors can only be presented through the illumination of light. Only when light acts on human vision can we feel the feeling of those colors. In complex color photography, the correct restoration and reproduction of color is the key to the success or failure of color photography. There are three elements in the correct reduction of color by light, one is the nature of light source, the other is the direction of light, and the third is the intensity of light. The nature of light source has a great influence on the color reproduction of objects, because the nature of sunlight and light is different, and the color temperature is also different. The color temperature of sunlight is 5400K, while the color temperature of light is only 3200 K. Under sunlight and light, objects will show different colors. For example, a red object looks bright red in the sun, but it will look red or purple in the sun. Because of the different light source properties, color reproduction is also different. The direction of light, when the same object is irradiated by light from different angles, such as direct light and scattered light, forward light and lateral light, reverse light and top light, the light irradiation direction is different, which makes the light and shade of the object different, resulting in different restored colors. Sunlight uses the same color of the same object on the same light receiving surface, and there is no distinction between light and shade, which leads to insufficient contrast between light and shade. Side light pairs can make the color of the same object have obvious differences in brightness. Backlight is difficult to restore the positive color of an object, and is often used to pursue the overall effect of color. The intensity of light also easily changes the hue, lightness and saturation of the object color. Visible light is an important modeling method of color photography, and choosing light is choosing color. Black and white photography is to choose different shades and shades to express the shape of objects, while color photography is to express art through colors. Black-and-white photography pays attention to the use of light, while color photography is more strict. Light can change the color tone, making the color effect more vivid and expressive. In the conception and creation of color photography, we should understand and analyze the nature of light source, the direction of light projection, the intensity of light brightness and the influence of light on the shape of objects. Only by mobilizing the artistic modeling of light on color and enhancing the expressive force of art can we foresee the color effect of the picture and create the artistic works of people born with dynamic feelings. The use of light in photography creation is ever-changing and flexible. Light is the basis of photography, and the art of photography is the art of light and shadow. Without light, you can't get the hue, and you can't form the artistic image of photography. So, we had the idea of photography. We should have the modeling consciousness of light, mobilize the modeling function of light, and give full play to the role of light in photographic art modeling.