How to get the ideal exposure?

Lead: Photography is the art of using light and composition, both of which are indispensable. But I will bring you some basic knowledge about exposure and some exposure skills that beginners need to know. I hope it will help everyone.

? What is the exposure histogram?

What exactly is exposure? Exposure in photography usually refers to the process that the photosensitive element (or film) of the camera receives the light emitted by the lens and records the image. Under ideal exposure, the bright and dark parts of a photo usually have good details. People often say that overexposure can be understood as that the photo is too bright and the bright part lacks details, while underexposure means that the photo is too dark and the overall color and details are difficult to distinguish.

Under ideal exposure, the light and dark parts of photos usually have better details.

? Overexposure (left) and underexposure (right) can often be judged by naked eye observation.

Knowing what exposure is, how to judge whether the exposure of a photo is appropriate? The first method is to see whether there are overexposure and underexposure problems in the photos by naked eye observation; The second one can be judged by the histogram of the camera itself. The horizontal direction of the histogram represents the brightness, and the vertical direction represents the number of pixels under this brightness, so the left side of the histogram represents the dark part, the middle represents the middle tone, and the right side represents the bright part. Normal? If there are no special creative requirements or lighting conditions, the histogram of the photo should be high in the middle and low on both sides. If the left side of the histogram is too much, the picture is too dark, and the right side is too much, which means the picture is too bright.

The dark and bright parts in the histogram of photos with relatively normal exposure are often balanced.

When the photo is overexposed, you can see that the histogram is obviously to the right.

When the exposure is insufficient, the histogram is obviously left.

I believe many readers have seen this and already know how to judge whether the exposure of their photos is appropriate. So how can we get proper exposure? In daily shooting, it is very important to keep the details of the picture as much as possible, so we need to understand the factors that affect the exposure of photos. The author will explain it to you from the aspects of metering, shutter, aperture and sensitivity, so that it is easier for you to get photos with accurate exposure when shooting.

? How to use photometry? Mode selection is particular.

First of all, let me talk about photometry. Photometry refers to the process that a camera determines the exposure of a photo by measuring the brightness of the reflected light of an object. Due to the different names of metering methods, the author divides the common metering methods into four types, namely evaluation metering, center focusing metering, spot metering and partial metering. Different metering modes will directly affect the exposure of photos. Let's take a look at how to choose metering mode. The operation is mainly based on Canon EOS 760D and Nikon D5500.

For beginners, evaluation photometry is still very common. '

It is a good choice to evaluate photometry when shooting large scenes (pictures from 500px).

Let's take a look at evaluation metering (that is, Nikon's matrix metering). This mode is based on the autofocus point, combining the subject and the whole picture to measure light, and then using the manufacturer's own algorithm to calculate the exposure value. Evaluation photometry is a very useful mode for novice photographers, which can meet the shooting needs of most subjects and make the whole picture more natural. However, it is often difficult to carry out photometric evaluation when the picture light is relatively large or the subject with backlight is photographed, so other photometric methods are needed.

Central average metering is suitable for the theme of central composition.

If the subject is centered, you can use the central focus average metering (picture from 500px).

Let's talk about central key average metering (Nikon's central key metering). As the name implies, this mode is to measure the light in the central area of the picture and the rest of the picture respectively. Compared with evaluation photometry, this mode pays more attention to the brightness of the central part of the picture and balances the brightness of the whole picture, so it is suitable for subjects with central composition such as portraits and group photos. However, when shooting, we always encounter complicated situations such as irregular composition and large light, which need to be solved by spot metering or partial metering.

Spot metering is suitable for shooting small objects.

Partial measurement can be understood as point measurement with a wider measurement range.

Spot metering or partial metering is suitable for environments with complicated light such as backlight (picture from 500px).

Finally, talk about spot metering and partial metering. When many users take outdoor portraits on sunny days, they will always encounter the situation that the face of the person in the photo is too dark. In fact, if they encounter such problems, they can re-compose the composition first to avoid backlighting. If it is inevitable, spot metering or partial metering will come in handy. Compared with the first two metering methods, these two metering methods have narrower metering range, so they are more suitable for accurate exposure of a point or area in a large backlight scene. The difference is that spot metering is smaller than partial metering (only near the focus), and users can choose these two metering modes according to the size of the subject.

? How to choose shutter aperture sensitivity shooting mode

After a brief understanding of the metering mode, the author will talk to you about the choice of shooting mode. Generally speaking, there are four decisive factors in photo exposure, namely lighting conditions, shutter, aperture and sensitivity. But the lighting conditions in our daily shooting are often natural light, which is beyond our control. Therefore, we need to control the shutter, aperture and sensitivity to get proper exposure. Accordingly, we need to use three shooting modes: shutter priority, aperture priority and automatic program.

Shutter priority mode is suitable for representing the subject of moving objects.

Record the vehicle trajectory with the slow door (picture from 500px).

Let's start with the shutter. What we usually talk about is actually the shutter speed, that is, the exposure time of the photo. When other parameters are fixed, the faster the shutter speed, the shorter the exposure time of the photo, and the darker the photo as a whole, while the slower the shutter speed, the longer the exposure time and the brighter the photo as a whole. Higher shutter speed can record the moment of object motion, while lower shutter speed can capture the trajectory of object motion, so when users want to express the motion state of objects, it is recommended to use? Shutter priority? Mode, and try to shoot multiple times with different sensitivities until the user's satisfactory exposure level is obtained.

Aperture priority mode is suitable for controlling the depth of field of photos.

I believe many readers like the blur effect brought by large aperture (picture from 500px).

First of all, the aperture photographer controls the amount of light that enters the lens through the aperture. With other parameters unchanged, the larger the aperture, the more light entering and the brighter the photo. In addition, large aperture can bring shallow depth of field, which is easy to cause blurred background, and is usually used for close-up of portraits and still lives; The large depth of field brought by small aperture is suitable for recording larger scenes. When users need to control the depth of field of photos, I suggest using? Aperture priority? Mode to select the appropriate aperture, and you can also take multiple photos repeatedly by adjusting the sensitivity to select the photo with the most appropriate exposure performance.

Program automatic exposure is suitable for recording scenes under different lighting conditions.

Under the P file, the scene under different lighting conditions can be dealt with by adjusting ISO (the picture comes from 500px).

Finally, talk about sensitivity. The sensitivity in the digital age can be understood as the sensitivity of photosensitive elements to light, which is usually expressed by ISO value. Simply put, with other parameters unchanged, the higher the ISO value, the brighter the picture. For beginners, program automatic exposure (P file) is a very useful gear. Users choose sensitivity and exposure compensation according to lighting conditions, and the camera will automatically choose the most suitable aperture and shutter speed. Generally, we will use higher ISO in dark light, but the noise caused by high sensitivity will affect the details of the picture, which needs the attention of users.

? Exposure compensation is also important. The ideal exposure is not absolute.

In addition to the shutter, aperture and sensitivity mentioned above, photographers can actually fine-tune their photo exposure through exposure compensation. Summary of usage of exposure compensation? White plus black minus? In the overall white environment (such as snow scene), the camera metering system will think that the scene light is too bright, so the photos taken are easy to be underexposed. At this time, it is necessary to make up for the underexposure by increasing exposure compensation.

Photographers can fine-tune photos through exposure compensation.

? When other conditions remain unchanged, when using Av files and adjusting exposure compensation, the camera can adjust exposure by changing the shutter.

Close-up of still life can be said to be a very popular shooting subject, and black base map is a very common close-up method. Because the black background is dark, the camera's metering system will think that the scene light is too dark, so the photo will be overexposed. At this time, we can highlight the main body by reducing the exposure compensation and darkening the background. It should be noted that exposure compensation is not an independent indicator. For example, when the user increases or decreases the exposure compensation under the Av file, the camera can adjust the exposure by changing the shutter.

This kind of still life close-up photo is dark as a whole, but this does not affect it as a good work (the picture comes from 500px).

Silhouette can bring the artistic effect of Gao Fancha (picture from 500px).