What letter is the shutter?

The shutter speed of a camera is expressed in seconds or its reciprocal. There are four commonly used shutter letter symbols, namely B, T, A and M, which represent different shutter modes of the camera and are used for different exposure requirements. The details are as follows: B stands for "light bulb", also known as "door B", and its exposure time is controlled by the shutter button. Press the button to open the shutter, release the button to close the shutter, and the exposure time can be controlled at will. T stands for "time", also known as "T gate", and its exposure time is also controlled by the shutter button. Press the button to open the shutter, instantly release the first curtain that can only open the shutter, and press the button again to close the shutter. A stands for "aperture priority", also known as "aperture priority". The camera will automatically select the appropriate aperture size according to the shooting situation, and the exposure time is calculated by the camera. M stands for "manual", also called "manual". The exposure time and aperture need to be adjusted manually, and the photographer needs to control the exposure himself.