How to measure light correctly in SLR camera

Lead: Do you have the same situation: the photos taken are completely different from what you think in your mind, either too dark or too bright. What's wrong? Let's see how SLR cameras measure light correctly!

Average photometry

In cloudy or low contrast environment, the whole area can get well-exposed photos by photometry.

Average metering is the most commonly used metering mode, which can give correct exposure results in most environments. In this mode, the camera will measure the light in each area of the picture, and after unifying the light measurement results, compare the data in the database to get the best exposure level in the environment. Since the development of photography, most shooting environments and conditions can provide quite correct exposure information, so in the automatic shooting mode, average metering is the preset mode. After the general public presses the shutter, they can generally take satisfactory photos, which has a considerable relationship with the popularity of photography.

Central key photometry

When the main body is centered, the central key can be used to measure light.

Most people always put the protagonist in the center when taking photos. Therefore, in the backlight and night environment, as long as the photometry in the central area is taken as the standard, and the EV is fine-tuned according to the brightness of the surrounding environment, you can take backlight or night shots to obtain the correct exposure image. In fact, this is also a' metering mode' developed when metering technology is difficult to measure light in a small area and there is no development of partition exposure. For advanced players who seldom use central composition and need more accurate exposure level, central key metering is a less used metering mode.

Spot photometry

In high contrast environment, if you want to show the shadow details, you can use spot metering to confirm the exposure.

Spot metering is a metering mode that advanced players love to use. Advanced players always like to challenge photography themes, such as Gao Fancha, backlight and twilight, and they also have their own opinions on the required exposure level. The general metering mode may not achieve the exposure effect that advanced players want. Spot metering is aimed at a small area, accounting for only 1~5% of the whole picture. Generally linked with the central focus, some models can be linked with the set focus. Using spot metering mode, you can measure the brightness of different areas in the shooting picture separately, and provide the information needed by advanced players. Does the player show light and shadow about the shooting focus, tolerance and picture? And so on, choose the right exposure value to shoot.

How do advanced players use spot metering?

Average photometric diagram

Schematic diagram of central key photometry

Schematic diagram of spot metering

How do advanced players use spot metering as exposure standard? Usually, in the weak light or Gao Fancha environment, neither the negative nor the photosensitive element of a digital camera can see clearly from the bright part to the dark part like the naked eye, which is called tolerance problem. When shooting this type of image, advanced players will use spot metering to determine the exposure. It is usually necessary to decide whether the work should focus on the bright part and ignore the details of the dark part, or focus on the dark part to overexpose the bright part. If both can present details, we must first set the middle tone, the bright part should not exceed +2EV, and the dark part should not be lower than -2EV.

After making a rough decision, spot metering is carried out with the central focus, and the exposure value of the bright part, the middle tone and the dark part is tested. After determining the exposure value of the required middle tone, the metering point (usually also the focus) is aimed at the middle tone area, and the numerical value is fixed with AE Lock or the aperture and shutter value are fixed with M mode, and finally the composition is photographed.