How much does the increase or decrease of exposure compensation affect the light quality when shooting portraits indoors with flash?

When you shoot a portrait indoors with a flash, the speed is synchronized with the flash, and the aperture adjusts the exposure. Why exposure compensation (or exposure compensation doesn't work)?

Exposure Compensation-Definition

During the shooting process of exposure compensation digital camera, if you press the half shutter, a picture similar to the final effect will be displayed on the LCD screen, and all focusing and exposure will be started. The exposure at this time is the exposure of the final picture. If the picture is obviously bright or dark, it means that the automatic metering accuracy of the camera has a big deviation, and exposure compensation should be forced, but sometimes the brightness displayed during shooting is different from the actual shooting result. Digital camera can browse the picture immediately after shooting, and at this time, you can see the brightness of the shot picture more accurately, and there will be no discrepancy. If the shooting result is obviously bright or dark, it is necessary to shoot again and force exposure compensation.

When the shooting environment is dark and it is necessary to increase the brightness, and the flash can't work, exposure compensation can be carried out to increase the exposure appropriately. When making exposure compensation, if the photo is too dark, the EV value should be increased. Every time the EV value increases, it is 1.0, which is equivalent to doubling the light input. If the photo is too bright, the EV value should be reduced. Every time the EV value is reduced, it is equivalent to doubling the amount of light entering. According to different cameras, the compensation interval can be adjusted in units of 1/2(0.5) or 1/3(0.3). When the photographed white object looks gray or not white enough in the photo, it is necessary to increase the exposure, which simply means "the whiter the more". This seems to run counter to the basic principles and habits of exposure, but it is not. This is because the camera's photometry often focuses on the central subject, and the white subject will make the camera mistakenly think that the environment is very bright, so it is underexposed, which is also a common problem that most beginners are prone to make.

Because the shutter time or aperture size of the camera is limited, it is impossible to reach the adjustment range of 2EV all the time, so exposure compensation is not omnipotent, and it is still possible to underexpose in too dark environment. At this time, it is necessary to consider matching the flash or increasing the ISO sensitivity of the camera to improve the brightness of the picture. 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/KOOC-0/5, were separated by/KOOC-0//2EV, so there were -2.0, -65438 +0.5,-/KOOC-0/.5,-/KOOC-. So there are -2.0, -65438 +0.7,-1,-1.7, -0.3 and +0.3,+1.0,+1.3.

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.

Exposure compensation for rich layers of negatives can generally be called correct exposure. Most modern cameras have an internal metering function. 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.

Exposure compensation-effect

Effect 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.

As can be seen from the above, exposure compensation plays an important role in the performance of the scene. Some experienced photographers often use the word "white plus black minus" to explain the essentials of exposure compensation. Because of the different reflectivity of various scenes, there is no specific standard for the compensation range. Therefore, photographers should form the habit of observing the scenery carefully, analyzing the balance and reflectivity between black, white and gray, grasping the exposure essentials they need from thinking and practice, and shooting wonderful works.

Exposure compensation-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%. 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.

Exposure Compensation-When to Use Exposure Compensation

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 "ten-level fuzzy gray image". .

2. The reflectivity of the main body is too high or too low. For example, shooting on a coal mining face, 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 the white wedding dress 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. [ 1]

Exposure Compensation-How to Use Exposure Compensation

How to apply exposure compensation? Generally speaking, in a white environment, the photometry is low and needs to be increased, and vice versa. A. When the shooting environment is dark and the brightness needs to be increased, the exposure can be compensated and appropriately increased when the flash cannot work. B. When the photographed white object looks gray or not white enough in the photo, the exposure should be increased. Simply put, the whiter the more, which seems to run counter to the basic principles and habits of exposure. Actually, it is not. This is because the camera's photometry often focuses on the central subject, and the white subject will make the camera mistakenly think that the environment is very bright, so it is underexposed, which is also a common problem that most beginners are prone to make. C, when you shoot in front of a bright background, such as in front of a sunny window, in front of a backlit scenery, etc. , increase exposure or use flash. D. When there is a beach, snow, sunny day or white background in front of you, increase the exposure and use the flash, otherwise the subject will be very dark. E. When shooting a snow scene, the reflection of the snow on the background light is particularly strong, and the photometric deviation of the camera is particularly large. Increase the exposure at this time, or the snow will turn gray. F, shooting black objects, when you look at the color change and gray in the photo, you should reduce the exposure to make the black more pure. G, when shooting in front of a black background, it is also necessary to reduce the exposure to avoid overexposure of the subject. (You need to increase exposure compensation to get enough exposure for night shooting) H. For night shooting, you need to turn off the flash, improve the exposure value and extend the exposure time of the camera to get gorgeous effects, which is especially important for automatic digital cameras without manual adjustment mode. Many people who use digital cameras feel that their night shooting ability is very poor. In fact, one of the important reasons is that they did not use the camera exposure method correctly. First, when it is cloudy and foggy, the environment is still bright, but the actual object illumination is obviously insufficient. Without exposure compensation, the photo may be dim. Appropriate exposure compensation, plus 0.3 to 0.7, can make the brightness of the scene more natural. J. In some artistic photography, such as taking high-profile photos, it is necessary to increase exposure compensation to form photos with great contrast and better express the author's shooting intention. Similarly, in some cases, if it is necessary to deliberately reduce the brightness of photos, the exposure compensation should also be reduced. Being good at applying and reasonably using exposure compensation can greatly improve the success rate of your photographic works, and take photos with clear pictures, appropriate brightness and comfortable viewing, thus improving the shooting quality.

Exposure compensation-principle

If the exposure compensation is fully automatic, the camera itself has an exposure compensation device, which generally increases or decreases by three levels according to the normal value. The basis of compensation mainly depends on shooting conditions, such as front light or backlight, front light, backlight and dark light, and the exposure should be increased; For example, under the same lighting conditions, the exposure of blacks will increase by 1 and 2 levels compared with whites; The intensity of the reflected light in the surrounding environment is large, so the exposure can be appropriately reduced, and the exposure can be appropriately increased if it is small.

If you set the shutter and aperture manually, you should know that the shutter and aperture determine the exposure. Then, according to the above, the purpose of exposure compensation can be achieved by appropriately increasing or decreasing the shutter speed and expanding or narrowing the aperture. General automatic exposure compensation is to modify the corresponding aperture value. If you want to pursue the dynamic effect of photos, you should use the shutter prerequisite function. That is to say, in addition to controlling the luminous flux, the shutter also has a main function of making photos have special dynamic effects. For example, the shutter speed is fast, which can condense the water column seen by the naked eye into water droplets, while the shutter speed is slow, which can also turn the water column of the same object into a water curtain. If you pursue this, you can fix the shutter first and make the aperture compensate accordingly. If the depth of field is different, we should use the first function of the aperture, that is, fix the aperture first and let the shutter speed make corresponding exposure compensation.