You can't always wait for the best outdoor light! When passive, we should first consider how to actively interfere with the negative effects of light on the picture. Lighting is not exclusive in the studio, and outdoor correction of light is also called lighting. I want to start with a photographic term - light ratio. It's about the bottom layer of lighting. Light ratio is one of the most important parameters in photography, which refers to the ratio of the brightness of the object's receiving surface to that of the shadow surface. Under the condition of natural light or artificial light distribution, the light receiving surface of the object is brighter, while the shadow surface is not directly illuminated (or less illuminated), but it still has a certain brightness due to scattered light (or auxiliary light). The ratio of the brightness of the receiving surface to the brightness of the shadow surface is commonly used to express the light ratio. The term "brightness of the receiving surface/brightness of the shadow surface" refers not to the brightness of the object itself, but to the intensity of the receiving light. For example, under uniform illumination, the brightness of black and white objects has a large proportion, but the light ratio is 1:1. The light ratio is not difficult to calculate. It does not necessarily have to use a professional external light meter.
It can also be accurately measured using a camera with manual function. The diaphragm values of bright and dark sides are obtained by measuring light points with a constant shutter (the principle of adding white to black and subtracting light) respectively. When the aperture value differs by one gear, the light received in the bright area is twice as much as that in the dark area, and the light ratio is 1:2. The difference between the two light ratios is 1:4; the three light ratios are 1:8; and the four light ratios are 1:16... And so on. More than one gear and less than two gears are 1:3. There is no need to be too precise.
Measurement of light ratio with external photometer
The ratio of light based on mathematics is of great significance to the effect of the picture. When the light ratio is large, the bright part will expose accurately and clearly, and the dark part will expose accurately. If the dark part is accurate, the bright part will expose excessively and form a high light. Either way, such pictures have high contrast. High contrast images bring strong visual tension, which is a biological phenomenon. Feedback in aesthetic psychology is often said to be a strong visual impact.
High light ratio, light metering with bright side
High light ratio, dark light metering
Conversely, when the light ratio is small, whether exposed in light or dark, the insufficiency or excess of the corresponding surface is limited, and the camera has a certain dynamic range. Dynamic range allows insufficient or excessive space, although the brightness varies, but the details remain. When the illumination environment light ratio is not large, the contrast of the picture is small, and the light part to the dark part is excessively soft.
We can't take it for granted to define the difference between big light ratio and small light ratio. According to the illustrations listed above, high contrast is more eye-catching than low contrast, but the use of light ratio depends on the subject matter. Simple examples: when portraying the image of a tough man, high contrast is more appropriate; when the performance is soft and sweet, it is too charming; when the plot is tense, it needs high contrast, and soap opera with high contrast is inappropriate. We can only list the contrast of different light ratios as follows to familiarize ourselves with the images created by different light ratios.
Low light ratio, low contrast
Effects of various light ratios
Photographers often refer to two words -- "tone" and "shadow tone". The former is an artistic term, while the latter refers to the former and is revised after photography. It has the same meaning in photography. There is such a definition in art. In sketch, objects show three aspects and five tunes when exposed to light. The three major faces refer to the bright, gray and dark sides; the five major tones refer to the highlight, the middle color (bright part), the boundary between light and dark, reflection and projection. The picture of photography also has the problem of tone, but it has been fully simplified in use. The tone in the photographer's mouth generally refers to two aspects. One is hard tone and soft tone. Hard tone means high contrast, soft tone means low contrast. It should be noted that the ratio of strong light is not necessarily high contrast, and the ratio of 1:1 is not soft but flat. Hard tones are explained in detail as excessive intensity from light to dark, and the lack of a gradient of grey between white and black in black-and-white photography. Having said that, I don't think it's necessary to waste any more soft explanations.
When the ratio of light created by illumination light is very large, but if the angle is controlled and the light decays slowly and excessively, a flexible picture can still be obtained, and the transition from light to shadow is very rich. Photographers call this phenomenon "hierarchy". The second meaning of tone refers to the high and low tones. Medium and low key were originally used in black and white photography. Black-and-white photography relies on black, white and gray to reflect the picture (lines on the other hand), white dominates the high-key picture; black dominates the low-key picture, containing a large number of intermediate gray information as the middle-tone.
High-profile works are composed of white to light gray tones, which account for the vast majority of the picture, with a small amount of dark tones. High-profile works give people a feeling of clarity, purity and lightness, but with the change of theme content and environment, they also produce a feeling of bleak, empty and sad. Low-key works with dark gray to black tone level accounted for the vast majority of the screen, a small amount of white plays a role in tone contrast. Low-key works form a sense of dignity, solemnity and fortitude, but in another environment, it gives people a sense of darkness, gloom and fear. The middle tone works are mainly gray tone, which is between high-key and low-key. The contrast is small and the level is rich. The image is composed of white to light gray, dark to black tone levels. The impression is rich in layers and exquisite in texture. Intermediate tone is one of the most common tone pictures in photography. In color photography, high and low tones still exist. It refers to the distribution of high brightness, low brightness and ordinary brightness in the picture. The visual effect produced is the same as black and white photography. Whether black-and-white or color, medium or low can be achieved by color design in the picture. But more often than not, photographers use light to reflect the tone of brightness. The serious overexposure is white, the extreme underexposure is black, and the black-and-white photographs of most scenes in the ordinary objective world are gray. It can be inferred that the accurate exposure is the middle tone. By choosing the lighting light and controlling the angle, we can realize all kinds of classification mentioned in the tone. Finally, let's make a popular definition of the tone. Movie tone is the tone of light and shadow.