How to measure light when taking pictures?

In fact, there is no fixed pattern for the use of light, but there is an interactive relationship between aperture and speed on hardware!

If you want to make good use of light at will, you must first master the basic knowledge of light!

Basic knowledge of light:

Photography is inseparable from light, and there is light to have a shadow. Photography is painting with light. How to use the relationship between light and shadow to form images and tones is a key in photography creation. Natural light in real life comes from the only sunshine. For the light projected on the object, not only the position and area of the shadow will change with the direction and angle, but also the impression and feeling of the object, including color tone and color tone, will show obviously different visual effects. Therefore, choosing the right light, including the right light direction and angle, is the first step that cannot be ignored in photography creation.

Generally speaking, light can be divided into three main types according to the irradiation direction, namely forward light, lateral light and backward light. Parallel light is light from the back of the camera. Because the light shines evenly on the subject from the front direction, the light receiving area of the subject is large and there are few shadows. It is relatively easy to measure light and control exposure when shooting. Even if the camera's automatic exposure system is used, there will generally be no exposure errors. In the case of smooth light, no matter whether the surface of the subject is uneven or not, due to the same light receiving situation, shadows are not easy to appear, which will lead to the lack of texture and three-dimensional sense of the subject, and the description of the subject tends to be dull; Side light refers to the light emitted from the side of the subject, which can make the concave and convex on the surface of the subject show a clear shadow, and the texture is an ideal light for the texture of the subject on the surface. Side light can not only outline the outline of the subject, but also reflect the three-dimensional sense, which is a common light in photography. Backlight refers to the light that the sun shines from the back of the subject. It is conceivable that in the case of backlight, the subject often becomes a silhouette, so it is relatively difficult to grasp the exposure. Backlight can set a striking and touching Phnom Penh on the outline of the subject. If handled properly, it can create a unique aesthetic feeling and shoot a sense of light and shadow full of dramatic effects. When taking backlight photos, if you measure the light according to the background or expose it according to the automatic program, you will often be underexposed. Be sure to pay attention to exposure compensation or fill light, which can be synchronized by reflector or flash during the day.

We know that the position of the sun changes from sunrise to sunset, so the light shining on the subject will change its angle as the position of the sun goes on. With the change of angle, the texture description of the main surface and the balance of shadows will directly affect the overall performance effect. Generally speaking, the light of about 45 degrees above the side of the subject is considered as the best lighting angle, which is equivalent to 10 in the morning and about 2 pm. Because it is also sidelight, the shadow of the subject is shorter at high angles and longer at low angles. The light in the same situation only comes once a day, and the choice of light angle cannot be taken lightly. This requires photographers to carefully observe the subtle changes of light in different seasons, different weather, different times, different directions and angles, as well as the emotional effects that can appear in the picture, so as to better use light flexibly according to the theme and ideas.

In addition, if we distinguish between light quality, light can be divided into soft and hard. Direct light is usually called "strong light", which generally refers to sunlight that is not blocked by clouds or other objects, or artificial light that directly shines on the subject, such as lighting lamps and flashlights. Under direct light, the light in the light receiving part and the shadow part is relatively large, the bright part is relatively clear, the shadow is relatively thick, the picture contrast is strong, and the stereoscopic impression is strong. But for some subjects, such as petals and human skin, when the contrast between light and shade is too large, it will give people a rough feeling. However, direct flashing often leaves an exaggerated shadow behind the subject, making the picture look too stiff and lack of aesthetic feeling, which is worthy of attention. Scattered light is a kind of soft light that does not produce obvious projection, also known as "soft light". For example, light on a cloudy day or when the sun is blocked by clouds belongs to scattered light. When artificial light is used, the light transmitted by soft paper or reflected by reflector is also scattered light. Because the light is not direct, but reflected from different directions to the subject, the shadow is light, the contrast is small, and the color tone is soft. On a cloudy day with thick clouds, because of the excessive diffusion of light, the tone and shadow will remain unchanged, and the picture effect will appear dull. Like a bright cloudy day, there are faint clouds blocking the sun, and direct light and scattered light are mixed together, which is generally recognized as the best "photo day".

Speaking of photographic light, there is another factor that must be considered, that is, the relationship between light and color temperature. In color photography, the color temperature of the light source directly affects the true restoration of the color of the subject. Color temperature is a spectral component of a light source and a measure of the color of the light source. It is expressed by approximate temperature scale K (Kelvin). Generally speaking, light sources with high color temperature contain more blue light components than red light, while light sources with low color temperature contain more red light components than blue light. The color temperature values of different light sources are different. During the day, the color temperature of sunlight also changes in different time periods. For example, the color temperature of sunlight at sunrise or sunset is about 2,000-3,000 K, the sunshine in the morning or afternoon is about 4,000-5,000 K, and the sunshine around noon is about 5,500 K. The color temperature of electronic flash is 5,500 K, and that of iodine tungsten lamp and photographic tungsten lamps is generally around 3,200 K. In color photography, there are two types of color films: daylight type and illumination type. After calibration, the balanced color temperature of sunlight color film is 5500K, and that of lighting color film is 3200K ... That is to say, sunlight color film must be used under a light source with a color temperature of 5500K to get a standard color reproduction, while lighting color film is suitable for a light source with a color temperature of 3200K. If sunlight color film is photographed under a light source with a color temperature of about 3200 K, the photo will appear orange-red. For example, the color temperature of sunlight is low in the morning and evening, and the photos taken with sunlight film tend to be warm and orange-red, which is also the reason. One way is to add a blue color temperature conversion filter in front of the lens, and under the light source of 3200K color temperature, the color temperature when shooting with solar film is improved to achieve normal color reproduction. Similarly, after the amber color temperature conversion filter is used to reduce the color temperature, the lighting color film can be used under the light source of 5500K K. For an experienced photographer, we must master the color temperature changes of different light sources skillfully in order to better grasp the color and tone of photos and fully reflect the theme of creation and the atmosphere of the picture.

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