What are the light metering methods? Introduction to light metering methods and techniques

What are the photometric methods of the camera? According to the different placement positions of the photometric elements, the photometric methods can generally be divided into two methods: external photometry and internal photometry. And because the inner light is consistent with the shooting conditions, automatic correction can be performed when changing the camera lens, changing the shooting distance, or adding a color filter. Almost all single-lens reflex cameras currently use this metering method. Next, let’s take a look at the metering techniques in different metering modes.

1. Camera metering methods

Since the structures and functions of various types of cameras are different, the corresponding metering systems and methods are also different. . At present, almost all digital camera light metering methods use TTL (Through the lens) and Auto Exposure systems to measure light through the lens.

The through-the-lens (TTL) light metering method is portable and easy to use. When using a filter or close-up lens cavity, it can simply and directly measure the light passing through the filter or close-up lens. The brightness value after the skin cavity is blocked and attenuated. Basically, there are four metering modes for digital cameras:

1. Average metering (also known as overall metering)

This is the most basic metering This metering method combines the brightness of various reflected lights of the subject in the viewfinder screen to obtain an average brightness value. The characteristic of average metering is that it is simple to use, but the metering accuracy is not high. When the light and dark distribution is uneven within the viewing range, it is difficult to determine the appropriate exposure directly based on the metering value. Especially when there is a large area of ??white or black matter in the picture, it often provides us with an inaccurate exposure value.

This type of metering system is mainly used in some low-end entry-level digital cameras.

2. Center-weighted metering (also known as? Center balanced metering?)

Center-weighted metering mainly measures the rectangular or circular (oval) range in the center of the viewfinder screen. The brightness within the rectangular or circular (oval) range will be averagely metered for other areas of the screen. The brightness outside the rectangular or circular (oval) range will have less impact on the metering results. As for the central area, it varies from camera to camera, accounting for about 20-30% of the entire frame.

Since the appropriate exposure value is read based on the brightness of the most important subject in the center of the screen, it is obvious that the accuracy of this metering system is higher than the average metering.

Another form of central metering is called "bottom metering". It is similar to central metering. It measures the lower half of the picture, thereby reducing the risk of paying too much attention to the sky. error.

The center-weighted metering system is generally used in mid-range small digital cameras. This metering mode is more suitable for portrait photography.

3. Spot metering

The metering range of spot metering is the area in the center of the viewfinder screen that accounts for about 2 to 3% of the entire screen area. Spot metering is basically not affected by the brightness of other scenes outside the metering area. Therefore, spot metering can be easily used to detect various areas of the subject or background.

Spot metering has high sensitivity and accuracy. But no matter what, you must remember that in order to achieve accurate exposure, the metering object should meet the requirements of 18% gray.

4. Matrix metering (also known as "zonal metering", "multi-area evaluation metering")

This metering mode is also called "intelligent" metering. It is an advanced metering method. The metering system divides the viewfinder into several areas (different cameras have different shapes and methods of division), sets metering elements respectively for measurement, and then calculates and compares the metering information of each area through the microcomputer in the camera, and refers to the area being measured. Based on the position of the subject, it is inferred whether the subject's light receiving state is backlight or general lighting, thereby determining the metering weighted proportion of each area. After all measurements are taken, the appropriate exposure value is calculated.

The matrix metering system of some cameras also takes into account the color of the scene when determining the required exposure. Matrix metering is currently widely used in some high-end digital cameras, which enables the camera to achieve better automatic exposure systems when shooting under various lighting conditions.

Emphasis: It is very important to understand the DC metering method in our own hands! Therefore, it is recommended that you carefully check the manual at hand. If the manual is not clear, you can check the relevant technical data online or buy it at your store. Check with your camera equipment store.

3. Metering techniques in different metering modes

1. Average metering mode

This metering mode is most prone to errors (fortunately (Yes, there are fewer and fewer digital cameras that only adopt this metering mode), because the metering system assumes 18% gray for each object measured.

In order to prevent incorrect exposure, you can consider using the following methods of controlling metering during shooting:

1) Many digital cameras now have an "exposure lock" function. How it works Yes, when we use the camera to measure the light at a special part of the shooting scene (the reflection of this part should be equivalent to 10% gray), and obtain the correct exposure data, we use the exposure lock control to fix the exposure condition, and then recompose the picture. , compose the picture according to your own requirements, and finally press the shutter.

2) For digital cameras that do not have "exposure lock" control but have "manual control" function, in this metering mode, you can also shoot in this way: that is, close to the scene and shoot appropriately The subject, let it fill the viewfinder, or aim the camera at other parts with a reflection value equivalent to 18%, set the aperture and shutter according to the exposure value at this time, and then come back to recompose and shoot.

Note: When we get close to the subject to measure the light, do not let yourself block the light, and make sure that the reflection value of this part of the scene being measured is close to 18% gray! Also, when measuring the object When the distance from the lens is inconsistent with the distance between the subject and the lens, be careful to control the focal length.

2. Center-weighted metering mode

Center-weighted metering is more accurate than the average metering mode, but problems similar to the above often occur, so you can still refer to the previous measurement. Light control methods and photography techniques.

3. Spot metering mode

Spot metering mode can calculate the exposure better. What we need to remember when shooting is to look for those places in the viewfinder screen where the light reflection value is equivalent to 18%, read the exposure, and it is best to use the exposure lock control to hold it until the picture is recomposed (if necessary), press Release the shutter.

Note: In the automatic shooting mode of a digital camera, you can first adjust the lens to accurately meter the light, then half-press the shutter, then move the camera to frame the picture and press the shutter!

4. Matrix metering mode

Using matrix metering mode, you can get about 95% good exposure effect, but even so, you may be deceived by the camera.

At this time, what we can do is to carefully study the "failed" PP, sum up the experience, and then make careful adjustments to make up (or reduce) the appropriate exposure when encountering similar shooting situations.