What does SLR camera metering mean? What role does photometry play in shooting?

Photometry serves for exposure, and a photo must be exposed correctly to look good. Incorrect photometry can cause photos to be too dark or too bright.

Function of metering: Without metering system, photographers need to decide the combination of aperture and shutter. At present, the general exposure modes of digital SLR are divided into program automatic exposure (the metering system gives the appropriate combination of aperture and shutter), aperture or shutter priority (the photographer sets the aperture or shutter, and the metering system gives the matching shutter or aperture) and manual exposure (the metering system will tell you whether the current setting is overexposed or underexposed).

The metering system of digital camera generally measures the brightness of the reflected light of the subject, which is also called reflection metering. According to the different placement positions of metering elements, metering methods can generally be divided into external metering and internal metering:

(l) External metering: In the external metering mode, the optical paths of the metering element and the lens are independent. This metering method is widely used in head-up viewfinder shutter cameras with sufficient sensitivity and accuracy. Single-lens reflex cameras generally do not use this metering method.

(2) Internal metering: This metering method is based on the lens, that is, TTL metering, which is consistent with the shooting conditions and can be automatically corrected when the camera lens changes, the shooting distance changes and the color filter is added. At present, almost all single-lens reflex cameras adopt this metering method.