The application of camera exposure

Answer 1

There were many applications for camera exposure in photography:

* * 1. Affects the image quality and effect **
1. * * Correct exposure to ensure image quality **
- The correct exposure was the basis for a high-quality image. In photography, the amount of exposure was directly related to the clarity of the image. If the exposure was correct, the sensor could accurately record the brightness, color, and other information of the scene, so that the photo had rich layers, clear details, and accurate color reproduction.
- For example, when taking landscape photos, the appropriate exposure could make the sky, mountains, trees, and other parts appear accurately. It would not lose the details of the highlight parts due to overexposed (such as the sky becoming white and the details of the clouds disappearing), and it would not lose the details of the dark parts due to insufficient exposure (such as the trees in the shadows becoming black and the trunk and leaves could not be distinguished).
2. * * The artistic effects of overexposed and under-exposed **
- Sometimes, for the sake of artistic expression, one could deliberately overexpose or under-expose the photos. For example, when shooting some abstract or dreamy scenes, appropriate overexposed could create a bright and ethereal atmosphere, while underexposed could be used when shooting low-key portraits or mysterious scenes, emphasizing the main body or creating a specific emotional atmosphere by letting part of the scene be in the dark. However, even if it was for the sake of artistic effect, it was necessary to control the degree of exposure to ensure that it did not affect the theme and instead added points to the theme.

* * 2. Cooperate with photography techniques **
1. * * Relationship with light sensitivity, aperture, shutter speed **
- The sensitivity, aperture, and shutter speed worked together to control the camera's exposure. When the sensitivity was fixed, the aperture size and shutter speed restricted each other to achieve the same amount of exposure. For example, if the aperture was opened one level (the amount of light entering was doubled), to maintain the same exposure, the shutter speed needed to be reduced by one level (the exposure time became half of the original). This relationship was known as the "reciprocation rate."
- In actual shooting, this relationship could be used to achieve different shooting effects. For example, when shooting a moving object, if you want to freeze the moment's movement, you need to increase the shutter speed. However, in order to ensure the same exposure, you may need to increase the aperture or increase the sensitivity accordingly. When shooting a landscape that requires a large depth of field, you can reduce the aperture and adjust the shutter speed according to the "reciprocation rate" to obtain the correct exposure.
2. * * Control of exposure in different shooting modes **
- * * Automatic mode (Automatic)**: The camera controls the exposure. The camera will analyze the scene according to its own light measurement system, and automatically adjust the sensitivity, aperture, shutter speed, and other parameters to obtain the appropriate exposure. This mode is suitable for beginners or for quick shooting in emergency situations, but it may not meet special creative needs.
- * * Sequential exposure mode (P)**: Although the camera controls most of the parameters, the user can choose from a set of parameters given by the camera. For example, the camera might give a combination of f/5.6 aperture and 1/125s shutter speed, or another combination of f/8.0 aperture and 1/60s shutter speed. The user could choose according to their initial requirements for depth of field or motion blur.
- * * Aperture priority mode (Av)**: The user controls the aperture size and exposure compensation, and the camera will automatically adjust the shutter speed according to the aperture value set by the user to achieve the appropriate exposure. This mode was very useful when shooting portraits, because the depth of field could be controlled by adjusting the aperture, making the character clear and the background blurred, and the main subject prominent.
- * * Shutter priority mode (Tv)**: The user controls the shutter speed and exposure compensation. The camera will adjust the aperture size according to the set shutter speed to obtain the correct exposure. For example, when shooting sports events, the photographer could set a fast shutter speed to freeze the movements of the athletes, and then the camera would automatically adjust the aperture.
- * * Manual Mode (M)**: User controls the sensitivity, aperture, shutter speed, and other parameters. It was suitable for experienced photographers. They could accurately control the exposure according to their creativity and understanding of the scene to achieve some special effects, such as deliberately overexposing or underexposing.

* * 3. Connection with Photmeter Mode **
1. * * Determination of exposure under different measuring modes **
- * * Rating: The camera will divide the image into several areas for measurement. It is suitable for scenes with relatively uniform light, such as most scenery scenes. The camera calculated a suitable exposure value based on the light conditions of each area to ensure that the exposure of the entire picture was relatively uniform.
- * * Central Average Metering **: Metering method with the central area as the main weight. It is suitable for subjects with a clear main body in the center of the picture, such as portraits, racing cars, etc. The camera would focus on the light in the center of the picture to determine the exposure. At the same time, it would also take into account the light in other areas of the picture to make the overall exposure more balanced.
- * * Local Metering and Spot Metering **: These two methods only measure light in a specific small area (such as the circle in the picture). They are more suitable for high-light environments, such as backlighting portraits or shooting artifacts. In this case, the photographer could accurately measure the light of the subject to avoid inaccurate exposure of the subject (such as the face in the backlit portrait being too dark or the exhibit being overexposed).
- * * Average Metering **: Average the image exposure information on the entire screen to determine the exposure. It is more suitable for outdoor or landscape shooting. It could give the whole picture a relatively average exposure effect, but it might not be accurate in the case of complicated lighting or a large ratio of the main body to the background light.
- * * Strong Light Metering (Some cameras have it)**: Focus on the bright areas of the screen to ensure that this part will not be overexposed. When shooting scenes with strong light sources or high-light areas, it could ensure that the details of the high-light parts were preserved.

* * 4. Relationship in the retouching of the map **
1. * * Post-production exposure adjustment **
- During the retouching process, the exposure could also be adjusted. However, when adjusting, you need to refer to the exposure of the main body in the picture, and pay attention to avoid the situation of blooming (the brightest part of the picture becomes white and loses details) and the dark part is dead black (the darkest part of the picture becomes black and has no details). The specific adjustments were based on the specific content of the picture and the desired effect. It required constant practice and reference to other people's works to grasp the degree of adjustment.
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