How to accurately control the exposure time of camera shutter?

This requires a comprehensive analysis according to the scene, objects, lighting conditions and the requirements of artistic creation at that time, and a corresponding numerical value is obtained. This value is not static, and it is greatly influenced by changes in external factors. That is to say, although many works show people the relevant data of shutter and sensitivity, it is difficult for people to shoot the same works, and even it is difficult for the author to shoot the same works in the same place for the second time.

First, the development of shutters

Camera shutter is something that controls the time when light enters the photosensitive part. In the early days, as long as the camera took off the lens cover and put it back on after a while, the shooting was completed. There is no special shutter, so people's expressions are very stiff, because it takes a long time to maintain a posture, and then there is an inter-mirror shutter. Using clockwork and spring to control the opening and closing of shutter blades, a delay mechanism is made. Then, in order to cooperate with high-speed continuous shooting to capture news photos and better serve newspapers, the electronic control steel shutter was invented. There are two ways to control the opening and closing time of the shutter: one is to adjust the shutter adjusting disc installed on the fuselage, and the other is to control it by rotating the adjusting ring of the lens.

Second, the understanding of the shutter

Shutters are expressed in numerical values as speed. What is the shutter speed? 3000 ? Does it mean that the shutter will open 1/ 3000? When the shutter speed per second is 1 second or longer, it is usually marked with ` or similar mark after the number, and 8` on the camera display screen indicates that the shutter will open for 8 seconds. Letters? b？ It means that as long as the shutter release button is pressed, the shutter will remain open until the shutter is released. It should be noted that if the shutter speed is too slow, slight jitter during shooting will lead to blurred picture. The longer the focal length of the lens, the greater the influence of hand shake on the picture, so it is necessary to use a safety shutter, which is basically a derivative of the lens used. Generally 1/? 125 s, which can meet the needs.

Third, the basis for setting the shutter speed

Different people will use different shutters in different scenes. At this time, it is necessary to determine the exposure time of the shutter from three aspects: the speed of the subject itself, the direction of motion and the distance between the subject and the photographer.

If the subject is moving very slowly or in a static state, a shutter with long exposure time is generally used; ? When the subject is moving fast, it is necessary to use a shutter with a short exposure time to freeze the high-speed moving picture, but in order to express the sense of picture and the sense of rhythm of movement, a slow shutter is sometimes used instead. For example, when shooting a dance picture, when the dancer's face is still and his hands and feet jump, shooting at the actor's face with a slow shutter can only make the actor's face appear as a real image on the screen, while the gesture or costume becomes a virtual shadow because of the rapid dancing, so that the picture will form a dynamic and static contrast. Make the picture more rhythmic.

Fourth, the shutter practice operation

Let's take motorcycle shooting as an example. When shooting from the back, the object moves slowly in the picture, so we can use a shutter with a long exposure time, such as1125s. When shooting the front of a motorcycle, the speed of the object in the view frame will be higher than that in front, so at least 1/? 300? S, you can't choose a shutter that is too slow, otherwise it will easily lose focus with the high-speed progress of the motorcycle. Of course, you can also adjust the shutter at a fixed point until the motorcycle is about to arrive, and then press the shutter to shoot the motorcycle from the side. The motorcycle moves relatively fast in the viewfinder. If you want to record its image clearly, you need to use11000 s, a speed above the shutter with a shorter exposure time.