Teach you how to use camera exposure compensation.

Digital camera is very easy to use, and you can know the actual shooting effect immediately after shooting. In addition, the contrast color can be adjusted in the computer later. Therefore, many photographers do not pay much attention to the accuracy of exposure in practice. In fact, the use of digital cameras requires very high exposure. In shooting practice, we should pay special attention to the use of "exposure compensation". When shooting some special objects, we should make full use of our accumulated experience in traditional photography to meet the exposure needs in specific situations.

First, why 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%. In the photographic system of the camera, no matter whether the object is black or white, it tries to display it as gray in the middle tone. 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, 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.

Second, how to make exposure compensation

In general, whether it is necessary to use exposure compensation, photographers mainly need to consider the following aspects.

1, when the brightness of the subject is relatively high, positive exposure compensation is needed.

For example, if the light-colored content such as blue sky and white clouds takes up a large area, we should consider increasing the exposure appropriately, at least half a step in the front light and one step in the side light.

If it is backlight, it should be handled according to the position of the sun, and it also depends on what you are showing. Usually, if you want to show the details in the picture accordingly, you should appropriately increase the exposure of 1.5-2. The more the sun is in the center of the picture, the more exposure should be appropriately increased (of course, attention should be paid to avoiding the strong sun to prevent the camera image sensor from being damaged. If there is no sunny day, such as red sun in fog, sunrise and sunset, etc. Because their brightness is low, it will not affect metering at all, so there is no need to consider exposure compensation).

In addition, when shooting snow scenes, fog scenes and other specific content, exposure compensation should be made as appropriate according to the characteristics that the performance object needs to show in a high-profile form at the end. Generally, it is best to compensate for the half exposure of 1 to 1 when shooting snow scenes, otherwise the final snow is not white and may turn gray due to insufficient exposure; It is best to compensate the exposure from half to 1 when shooting the fog scene, otherwise the fog scene will be dark and close to the night scene, which is obviously not ideal.

There are also special objects such as shooting a white stage, people wearing white clothes, hospitals or laboratories with high ambient brightness, and large aircraft with the sky as the background. Appropriate exposure compensation should be made according to the relationship between the shooting object and the background.

2. The low brightness of the subject needs negative exposure compensation.

Usually, when shooting city night scenes, there are two main ways to prevent overexposure except buildings, streets or other high-brightness content occupying the main area of the picture. One is to expose the main performance objects by spot metering; Another method is to use exposure compensation to reduce exposure appropriately according to the actual situation. Generally, when the shot picture (especially the photometric sensitive part in the middle of the picture) occupies a large area of the sky, it is often necessary to reduce the exposure by two or more steps.

In addition to shooting night scenes, when shooting other scenery themes, such as summer shade, mountain scenery in backlight state, etc., negative compensation for exposure should be adopted to appropriately reduce exposure. There are people who wear black clothes, dark textiles, etc. And it is necessary to reduce the exposure to obtain normal tone recovery. Because digital cameras also determine the exposure by measuring the reflected light of the subject, if the photographer does not make corresponding negative compensation for exposure when dealing with objects with obviously low brightness, the final result will be neutral gray tone. Obviously, it's hard to accept that objects that are obviously black or dark are finally transformed into neutral gray-based images.

3. When the relationship between subject and background is complex, it needs to be handled flexibly.

There are two main situations:

A. The background brightness is high and the subject brightness is low, so it is necessary to make positive exposure compensation and increase exposure.

This often happens when shooting people at meetings. Sometimes, when a figure sits in front of the window, there is sunshine behind the window, the background appears bright, and the figure is obviously dark. At this time, if the flash is not used to fill the light, exposure compensation is needed. After general exposure compensation of 1 or so, the facial level of the characters will be obviously improved. Also, when shooting a backlit portrait, if the background includes a large area of sky, water and other high-brightness objects, the contrast should be improved by positive compensation or other auxiliary light, otherwise the reflection of the main characters will be affected. Even if people are brightened by image processing software later, the quality of photos will be affected by obvious noise.

B the background brightness is low and the subject brightness is high, so negative exposure compensation is needed to reduce the exposure.

This situation is often encountered in stage photography. Generally, when one or several actors perform on the stage, in order to attract the attention of the audience, they often use one or two spotlights to shine on the characters. At this time, the other backgrounds on the stage are almost all black because there is no direct light, so there is a great contrast between them. Unless the performer happens to be in the center of the picture and you use spot metering mode, you must make negative exposure compensation, otherwise it is easy to overexpose.

Third, learn from the experience of black-and-white photography to control the brightness of tones.

As far as determining the specific scope of exposure compensation is concerned, if photographers have rich experience in black and white photography, they will be more handy in exposure compensation. Because black-and-white photography is mainly expressed through three levels: black, white and gray. Generally speaking, as long as most of the content in the picture is converted to neutral gray tone in the later stage, it can be exposed normally; In the later stage, most of them turn to black as the main tone, and the negative compensation exposure needs more than 1 file; It is mostly white or close to white in the later period, so it is necessary to make positive compensation for the exposure above 1.

Under very complicated shooting conditions, it is a key moment to test the photographer's shooting technology whether he can distinguish and determine which objects need exposure compensation when shooting. There is a very simple principle to check whether the photographer confirms that the exposure is appropriate, that is, after processing according to the principle of appropriate exposure compensation, that is to say, the exposure indication obtained by measuring the reflected light with the camera and the exposure parameters obtained by the photographer's own appropriate exposure compensation should be the same as the' exposure indication' measured by an independent exposure instrument (mainly measuring the incident light, which is not affected by the reflectivity of the subject), and the exposure should be treated in this way, even if it is a strict color reversal film.

Fourthly, we should not pin all our hopes on the post-processing of image software.

If you have certain requirements for your own image quality, you should first consider making the exposure accurate, properly use the exposure compensation function, and accurately reflect the original appearance of the subject. Because even if the brightness and contrast of digital images can be modified later, one thing is certain. Only the image with accurate exposure can be easily modified, and it is possible to get better image quality, and there will be more room for manoeuvre when necessary post-processing. Therefore, photographers should pay attention to the early shooting, and never neglect the application of exposure compensation because of the factor that "digital images can be modified later".

Of course, if what you shoot is very important and it is really difficult for you to grasp the exposure, you can also set the camera to "surround exposure" mode and compare a few more to accumulate experience, so that you can get a digital image with accurate exposure in the real sense and get a higher quality photo in the later output.

In a word, users of digital cameras should learn from traditional photography experience when shooting objects with special brightness, and make corresponding compensation and adjustment for exposure parameters according to their experience and their own understanding of theme performance. Making full use of the exposure compensation function is of great help to obtain high-quality original digital images and to better play the role of materials in the later period.