Shulou(Shulou.com)11/24 Report--

When we observe a scene, we will determine the light and shade according to the light reflected into the eye, and when the camera is shooting, there will also be a process of judging the light and shade of the scene, which is photometry.

We may not notice this process when we shoot, but it plays a big role when we shoot, and it also gives us some reminders:

If you happen to have a camera next to you, you can try it now, set the shooting mode to M file, simply set the basic parameters according to the scene, and then aim at an object and half press the shutter, then observe the "light ruler" on the shoulder screen or home screen:

That is, this horizontal scale table is the reference data fed back to you by the camera according to the light of the object scene: the 0 in the middle means the exposure is normal, the left side means the picture is underexposed, and to the right it means the picture is overexposed.

So is the data fed back to us by the camera reliable?

It's hard to say. The camera has its own system for measuring light, that is, 18% reflectivity. If you are interested in the specific principle, you can check it yourself. Remember a simple principle here: the camera will shoot objects in varying degrees of gray. If the proportion of white in the scene is too much, the reflected light will exceed 18%, and the photos will be gray and dark, that is, underexposed. If the proportion of black is too much, then the photo will also be gray and bright, that is, overexposed.

This is the principle of "white plus black subtraction". In our daily shooting, if we shoot this kind of scene, we can appropriately adjust the exposure compensation, such as shooting large white walls, snow scenes, etc., we can appropriately increase the exposure compensation; large black scenes reduce the compensation.

There is a large amount of white in the picture, and the exposure compensation should be properly improved. on the whole, the photometry of the camera itself is not 100% accurate, and many professional photographers will use professional gray cards to achieve accurate exposure, for us, most scenes do not need to be so professional, mastering basic photometric skills and reasonable use in the later stage can make up for the deficiency in the early stage to a certain extent.

There is another way to help us achieve accurate exposure. The camera comes with a variety of metering modes, which we can set according to different scenes and our own needs.

In general, most cameras support these metering modes:

1. Evaluation photometry uses a very common photometric mode, which is also the default photometric mode of many cameras. In this mode, the camera will divide the picture into multiple areas, measure each area independently, and then calculate the average photometric value of the picture.

Canon 70d photometric setting screen, effective for the backlight main body does not mean that the effect is good, the photometric mode is suitable for the whole scene with uniform light and small light and shade contrast, and the exposure of the picture is basically accurate.

Shun light, side light scenery, portraits and so on are all suitable for this photometric mode.

two。 The central average photometry uses the more common photometric mode, because many camera users are accustomed to placing the subject in the middle of the picture, and this mode is also designed to cater to this shooting mode. the photometric data of the central position of the picture (about 2 beat 3) is used as the main reference, and the photometric data of the surrounding edge is used as the auxiliary.

The performance of this model is stable in most scenes, and portraits and scenery themes can be used.

3. Central part photometry (local photometry) the central part photometry is similar to the central average photometry, but the central part photometry only selects the central part of the screen (about 3% color 12%) as the reference data.

Therefore, this mode is more suitable for scenes with complex environment and large light contrast, such as backlighting, indoor stage, concerts and so on.

Measure the light in the bright area to avoid overexposure. Spot photometry can be regarded as a "reduced version" of photometry in the central part, which measures about 1% of the area in the picture. Compared with the central part, it is more accurate and can better grasp the details of the complex environment.

However, because the photometric area is too small, the use of this mode requires a certain degree of observation and operation experience, which is generally more suitable for fixed camera position shooting fixed angle of view.

When we want to shoot the moon without a suitable lens, the proportion of the moon in the picture is too small, we can use this photometric mode to accurately measure the moon to avoid forming a large blurred halo, which can be cropped later. You can also get a pretty good picture of the moon.

5. Multipoint photometry is a more complex photometric mode, when using this mode, we can measure light in multiple areas at the same time, for example, first measure the light of the subject and lock it with AE, and then measure the background and other areas, and the camera calculates the final exposure value according to the average value of these points. This model is suitable for complex and high contrast environments.

Photometry is essentially an intelligent calculation and adjustment function of the camera, which looks complicated. In fact, most of the work is done by the camera itself. We only need to master the principle and use it reasonably in combination with practice.

This article comes from the official account of Wechat: play some Photography (ID:wakexiao), by AGER

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