Range effect of exposure compensation

Almost all digital cameras have the same exposure compensation range, which can be added and subtracted within plus or minus 2EV, but the addition and subtraction are not continuous, but jump at intervals of 1/2EV or 1/3EV. Early old digital cameras, such as Kodak's DC2 15, were separated by 1/2EV, so there were -2.0, -65438 +0.5,-1,+1. So there are -2.0,-1.7,-1.3,-1.0, -0.7, -0.3 and +0.3, +0.7,+1.0,+/kloc-.

Generally speaking, the smaller the brightness contrast of the scene, the more accurate the exposure, otherwise the deviation will increase. There are high and low grades of cameras. If the grade is high, the measurement will be more accurate, and if the grade is low, the deviation will increase. If it is a traditional camera, the film tolerance is relatively large, and the exposure deviation will not be a big problem within a certain range, but the CCD tolerance of a digital camera is relatively small, and a slight exposure deviation may affect the overall effect.

In a word, the adjustment of exposure compensation is determined by experience and sensitivity to color. Users must compare the image quality, sharpness, reduction and noise under different exposure compensation in order to take the best photos.

Generally speaking, a negative with rich layering can be called correct exposure. Most modern cameras have the function of internal metering. In most cases, shooting according to the data provided by the exposure meter can make most negatives get basically correct exposure. This is because the exposure meter reads 65,438+08% gray tone, and 65,438+08% gray is the average light value in our daily life scenes, such as our skin color. However, the correct exposure is not equal to the best exposure, especially when white or bright objects are dominant in the picture, there will be obvious deviation if shooting only according to the photometric data of the camera, that is to say, the white objects, bright objects and dark objects in the picture are all 18% gray scale, which is naturally unsatisfactory. Therefore, exposure compensation plays an extremely important role in the absence of incident exposure meter or gray board. Our common cameras with automatic exposure function generally have exposure compensation function, while cameras with manual exposure need to compensate exposure by controlling shutter and aperture. From the picture below, we can see the results of different exposures of white objects and black objects.

Increase exposure rate

According to the white tea set, photometric exposure, the main body of the picture is gloomy.

The main color tone is improved by adding 0.5EV (half stop) exposure on the basis of the original metering.

Based on the original photometry, the exposure of 1EV is increased (1), which correctly represents the white subject.

(2) Reduce exposure

Photometry and exposure are carried out according to the black subject, and the tone of the black subject is light.

On the basis of the original photometry, the exposure of 0.5EV (half stop) is reduced, and the color tone of the black subject is improved.

On the basis of the original photometry, the exposure of 1EV( 1) is reduced, and the black color of the subject is correctly represented.

Exposure compensation

Like traditional cameras, the photometric exposure system of digital cameras has a very basic principle when processing images, which is to restore all subjects according to the neutral gray brightness of 18%. Therefore, in the photographic system of the camera, no matter what the original brightness of the object is, it should be displayed in a medium brightness tone at last. Therefore, in actual shooting, the photographer still needs to make corresponding judgments according to the complexity of the shooting scene, and only in this way can the ideal density and color reproduction be guaranteed.

Most portable digital cameras have positive and negative exposure compensation, which can meet the shooting needs in most complex situations. As for some advanced single-lens reflex digital cameras, the exposure compensation even reaches plus or minus five files, which can meet the shooting needs in extremely complex lighting environment. The design of digital camera and why manufacturers design and handle the camera in this way are enough to explain the important significance of exposure compensation to photo quality, which is a technical point that can not be ignored. If you are using a camera with an exposure meter or automatic exposure function, you should consider exposure compensation under the following circumstances;

1. Backlight photography. If your subject is facing away from the bright sun, that is, in the case of backlight, then in order to accurately show the details of the subject, you must make exposure compensation, otherwise, you will either take a silhouette or a gray image with unclear levels.

2. The reflectivity of the main body is too high or too low. For example, shooting on the mining face of a coal mine, or shooting a bride wearing a white wedding dress in a high-profile background, if the exposure given by the exposure instrument is not compensated, then the dark coal and white skirt recorded on the film may be the same gray tone of 18%.

3. Reciprocal exchange rate is invalid. If the exposure time is too long (more than l/ 10 second) or too short (less than11000 second), the exposure curve of ordinary film will be distorted. If you still shoot according to the exposure combination given by the exposure meter, there will be underexposure, and if you use color film, there will also be problems of color saturation and color temperature deviation.

4. Shoot moving objects in extremely weak light. Sometimes the light at the shooting scene is particularly weak, the artificial light illumination is insufficient, the subject is moving, and the film sensitivity in the camera can not meet the requirements of spotlight. At this time, it is also necessary to make compensation, that is, reduce the given exposure within the allowable range, control the number of steps to reduce the exposure during development and carry out forced development (or "sensitized development"), and also get a clear negative.