Brief introduction of SLR how to adjust exposure compensation

When we are shooting, we always hear people say that our photos are underexposed or overexposed. For photographers who are new to the camera, they often just know how to extend and shorten the exposure time, or open and narrow the aperture to correct this "overexposure and underexposure". However, the result of this is often more and more confused in the face of exposure. In fact, for exposure, there is always an important parameter in the camera to remind us, that is, exposure compensation.

Exposure compensation is not a verb or an action, but a name. Exposure compensation is a parameter used to quantify the brightness of photos.

The reason why we can see everything in the world is that light shines on objects and then reflects into our eyes to become an image. If extreme white reflects 100% of the light, then extreme black completely absorbs the light and reflects 0%. Gray between extreme white and extreme black does not reflect 50% of the light as we thought. After precise measurement by scientists, the gray in the middle actually reflects 18% of the light. So the brightness in the middle is also called 18 degree gray.

▲ Different brightness and 18 gray.

If we use the camera AUTO to take pictures in different scenes at different times, we will find that although the intensity of light varies greatly, the brightness of the photos taken is not much different. This is because the camera will set the corresponding aperture, shutter and sensitivity according to the metering system when it is in automatic mode, thus taking a photo of 18 gray-not too bright, not too dark, just right. If we quantify this just-right brightness, the exposure compensation for such a photo with medium brightness is 0.

▲ Photos with exposure compensation of 0.

The exposure compensation of general cameras ranges from -2 to +2, and some advanced cameras range from -3 to +3. If shooting the same scene, the brightness of the photo with exposure compensation of-1 is half that of the photo with exposure compensation of 0, and the brightness of the photo with exposure compensation of -2 is 1/4 of the photo with exposure compensation of 0. On the other hand, the brightness of photos with exposure compensation of+1 is twice as high as that of photos with exposure compensation of 0.

For many scenes, 18 gray is not a good brightness. For example, if we shoot a snow scene, the camera's metering system will not know whether it is snow or white, and will foolishly think that it is too bright here, so if the exposure compensation is 0, then the shot snow scene is a scene covered with "gray" snow. If we shoot a coal yard, the camera will foolishly think that it is too dark here. If the exposure compensation is 0, the photos taken are all "gray" coal. None of this is what we want.

Therefore, when shooting the snow scene, it is necessary to appropriately increase the exposure compensation, so as to make the snow white; When shooting coal piles, we should reduce the exposure compensation and make the coal black.

▲ Appropriate increase in exposure compensation snow is white.

For beginners, one thing to remember is that exposure compensation can't be mistaken: exposure compensation has nothing to do with the brightness of the environment when shooting, but only with the brightness of the finished photo. Even if it is dark around, if exposure compensation is added, the final photo will be very bright; Even if the surrounding lights are bright, if the exposure is reduced, the final photo will be dim.

From the above description, we know that exposure compensation is actually adjusted in some special scenes or special circumstances. For example, the object you shoot is bright and occupies a large area in the picture. In order to reflect the original brightness of the object, you should make the photo brighter and increase the exposure compensation. Similarly, if the object itself is dark and occupies a large area in the picture, in order to reflect the original color of the object, the photo will be darkened to reduce the exposure compensation.

In addition, sometimes we want to explain that cheerful scenes will also improve the brightness of photos and increase exposure compensation. For some depressed and gloomy subjects, it is necessary to appropriately reduce the brightness of photos and reduce exposure compensation.

▲ Sad scenes should reduce exposure compensation.

The brightness of many photos can reflect the photographer's intention, so it can be said that exposure compensation is an important parameter to reflect the photographer's intention in photos.

On our camera, as long as it is not a pure automatic camera, we can adjust the exposure compensation. If your camera only has automatic function, forget it. General exposure compensation can only be adjusted in P (program exposure), A (aperture priority) and S (shutter priority). Although exposure compensation cannot be directly adjusted in M (Manual Shift), it can be controlled by adjusting aperture, shutter and sensitivity.

▲ exposure compensation ratio in camera shoulder screen

Exposure compensation usually appears in the form of scale or numerical value in cameras. By default, the exposure compensation is 0.

An advanced SLR camera will have two thumbwheels, one for P, A and S files to adjust exposure compensation. Professional integrated lens DC is also designed in this way.

Entry-level cameras generally have only one thumbwheel, which is used to adjust the exposure compensation of P file. If you are in gear A and gear S, you can adjust the exposure compensation by pressing the exposure compensation button and turning the wheel.

This design will also be used for general body lens integration DC, so a single-wheel camera usually has an exposure compensation button. The position of the button is generally near the dial wheel or the right shoulder of the camera, which is convenient for everyone to hold down the exposure compensation button with one finger and dial the dial wheel with one finger.

Many fashion card machines are difficult to see the exposure compensation button on the fuselage because of its simple design. Some need a three-dimensional wheel to select exposure compensation by pressing the wheel, and some touch-screen cameras can click the exposure compensation button on the screen, depending on the camera manual.

▲ exposure compensation in touch screen camera

It is worth mentioning that many retro cameras, such as Canon G 12 or Fuji X 100, have independently designed exposure compensation dials. It is more convenient to adjust.

▲ Exposure compensation turntable Conclusion: There is no correct or wrong exposure for a photo. Any kind of exposure is the embodiment of the photographer's intention. Mastering exposure compensation is the first step to properly express your shooting intention in photos!