What's the difference between matrix metering, average metering, evaluation metering and division metering?

What are the uses of 3D color matrix photometry, 2 1 area evaluation photometry and 14 area honeycomb photometry in professional and quasi-professional cameras? Using these "advanced" and complex measurement modes, it seems that more accurate measurement results can be obtained, but it can't be done in practice. On the contrary, using the "original" simple spot metering or center focusing metering mode, and properly using exposure compensation, more accurate metering results can be obtained.

The content about metering in the camera manual will generally focus on these advanced metering modes, which makes people think that metering using this mode is more accurate, such as:

2 1 area evaluation photometry. With this advanced metering mode, Canon has once again improved the much-appreciated performance of EOS series. When the camera is aimed at the subject, the 2 1 area will evaluate the most suitable exposure for photometric measurement. The camera identifies the subject according to the focus, and then measures the brightness levels covering the main metering area, the sub-metering area and the reserved metering area, thus calculating an optimal exposure. Relevant data are processed and evaluated by a brand-new algorithm. This means that users can take photos with the most suitable exposure at any time, even if they are shooting in the back light, or the subject has extended to two or more metering areas. This mode will automatically identify the most suitable metering area, making the metering evaluation more accurate than ever before.

3D color matrix photometry. The metering mode is based on the brightness of the object, the contrast of the object, the focus area selected by the photographer, the distance from the object to the film plane, and the color of the object. The main feature of 3D color matrix photometry is that it is equipped with a brand-new photometry sensor, including 1 005 particle CCD. This sensor is specially designed for single-lens reflex camera, and has a series of characteristics such as high sensitivity, high precision and wide dynamic range detection. Each particle in the photometric sensor contains an R (red), G (green) or B (blue) filter. Therefore, it can not only measure the brightness and contrast of the scene like a traditional photometric sensor, but also evaluate the color of the scene. If the color of the subject is included in the photometric factors, the exposure result of the subject will be closer to nature. The traditional metering mode is based on 18% medium gray surface reflectivity, and the exposure is mainly determined by the brightness and contrast of the scene as basic elements. However, there are as many as five factors to determine exposure by 3D color matrix photometry. The photometry system will integrate these factors, calculate through an efficient microcomputer, and rely on the cooperation of the database to formulate more accurate exposure control.

In principle, these advanced metering modes are: increasing the focal length, distance and other information by means of zoning and color separation to obtain more information, and combining the exposure experience of a certain number of typical photos, the metering results are obtained through complex operations.

At present, the camera can't solve two important factors in metering technology, so these advanced metering modes can't accurately measure light under any circumstances.

1. The camera can't know the gray level of the object, and the camera can't tell whether the object is black or white. The photometry mode assumes that the subject is 18% gray, and exposure compensation must be carried out on the basis of photometry when shooting objects with different gray levels.

For example: shoot a snowfield, shoot a coal. Use spot metering or central key metering and then use the compensation method of "white plus black minus". 3D color matrix photometry can only determine the color (hue and purity) of the object, but not the gray level. It is not enough to know the color, so you can't get the correct exposure. 2 1 area evaluation photometry and 14 area honeycomb photometry also can't get gray information.

(to restore the correct gray scale, we must first expose it accurately. In the process of photometry, we don't know how to expose accurately, so we can't know what the gray level is. )

2. The camera can't accurately know the photographer's shooting intention. The camera can't know exactly which parts are the main body of the picture and needs accurate exposure (the exposure of the background part can be ignored); The camera can't know whether the photographer wants to take high-profile photos, low-key photos or silhouettes. Cameras usually judge the subject of a picture by focusing, which is not very reliable, such as when the distance between the subject and the background is the same. In addition, it is difficult for the camera to determine how big the object is.

For example, the picture includes half the sky and half the ground, and the brightness difference between the sky and the ground is quite large, so it is impossible to take into account the exposure of both. Photographers can choose which is the focus of performance and ensure that one of them is exposed correctly. Cameras can't make the same choices as photographers.

Because these advanced metering modes sometimes make mistakes, we will consider exposure compensation when they make mistakes. Worst of all, when using these modes, it is difficult for us to know when and how much compensation should be made!

To know when and how much compensation should be made, we need to know the specific algorithm of these metering modes or the specific algorithm of exposure compensation, and the exposure compensation value can be obtained through complex operations. On the one hand, these algorithms are not public; On the one hand, these calculations are too complicated to be completed by people. It is also extremely unreliable for photographers to compensate for exposure through experience. The timing and deviation of these advanced metering modes are often very strange. The camera manual will say that exposure compensation is not recommended when using these advanced metering modes. On the contrary, exposure compensation for spot metering or central focus metering is relatively simple and reliable.

Are these advanced metering modes still useful? These metering modes may have little deviation in most cases, and the only advantage is to save trouble-there is no need to consider exposure compensation. Suitable for beginners and people who don't want to spend too much energy thinking about how to take good photos. Combined with the program exposure mode (P file), you can realize one-point-one shooting. However, these people generally don't buy professional cameras that are big, heavy, fully functional and complicated to operate. These advanced metering modes are most suitable for configuration on a fool's camera.

Finally, consider what metering mode a professional camera should have. Spot metering or center focusing metering mode is enough, and exposure compensation is considered by the photographer. If it is to be improved, it can be developed in the following aspects: the accuracy of photometry should be improved, preferably reaching 0.1ev; ; The measuring point angle is variable, and the minimum value is 1 degree; The position of the point measurement on the screen can be moved and associated with the focus.

PS。 Masters said: Serious photographers use independent exposure meters to measure light.

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Reply to the landlord. I happen to be studying and thinking about similar problems. Here's what I learned from my research:

1 What is photography?

In western languages, photography literally means drawing a picture with light. This is probably the most popular definition of photography, and it is also the most easily understood concept by ordinary people (Westerners)-the basic task of photography is clearly stated: drawing pictures with light.

2 What is the correct exposure?

Since we paint with light, the photographer should be able to control the exposure independently. A correctly exposed photographic work is an exposure combination that can faithfully reflect the photographer's shooting intention. This may be a photo in which the subject is too bright, or it may be a photo with a dim picture, or it may be a photo that is most acceptable to most people-the image is clear and the color is true (or richer than the real color in nature). No matter what the tone of the photo is, as long as it is the tone conceived by the photographer before pressing the shutter, this is a correctly exposed photographic work.

Can I control matrix metering?

Matrix photometry is to calculate the photometric values in each matrix through the built-in program and give an exposure combination. The problem is that photographers can't know how computer chips are calculated. Using matrix photometry means that the photographer gives up the control of light. For example, let two masters with different styles shoot the same scene with the same camera at the same time. If we use matrix photometry and automatic exposure, we will get two photos with the same tone-matrix photometry and automatic exposure eliminate the difference in tone and color between different styles of masters! Personality among different photographers is deprived by computer programs!

When and who needs matrix photometry?

-when the light contrast is not big.

Beginners and people who want to take photos with excellent tone and vivid colors quickly, and all photographers who don't want to think.

4 digression:

My colleagues and I came back from a business trip, and we looked at each other's photos. My colleagues who went with me were all surprised. I used a camera 50 years ago (there is no metering, it can only be regarded as a cassette that can only focus and adjust the shutter speed). The photos (negatives) taken by the Sixteen Rules of Sunshine are even more pleasing to the eye than those taken by Nikon and Minolta's automatic film machines-the images are clear and sharp, the colors are naturally restored, and the layers are strong-of course.

Fifty years ago, before matrix metering and partition metering, many people could take lovely photos with cameras with simple functions as focusing mechanism and shutter speed setting. Today, 50 years later, an old camera can only be regarded as a "cassette" compared with modern cameras with complex functions. As long as it follows the basic techniques of photography, it can also take lovely photos.