Digital Camera Shutter

The digital camera shutter is the mechanism which opens and closes the pass of light to the film. When it's closed the film remains in total darkness and when it's opened it is exposed to light. The time it stays opened is called the exposure time .

When photography was young exposure times were many seconds or minutes. The shutter used then was the lens cover. With better film sensibility, shorter exposure times were possible and therefore harder to control manually.

Nowadays a camera's shutter is a precision instrument which regulates the movement of a dark metal or cloth barrier inside the camera, which allows a large range of exposition times. In a digital camera the amount of light that comes in contact with the sensor when you press the trigger is registered. A light-proof barrier is not necessary since the sensor is constantly exposed to light. Another word used for exposure time is exposure speed . The exposure speeds on all cameras are fractions of seconds which are chosen so that everyone of them is a time double that of the last speed and half of the next one.

On most cameras you find the following speed range: 1/1000 of a second, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2 a second. One second and greater times are available in the “B” position on the speed scale.

The shutter's speed control is the second basic control on the camera, and is used to regulate the duration of the exposure. Speeds are usually indicated without using the numerator: 100, 500... 1. Remember the exposure doubles each step to the right and gets cut in half with each step to the left. For example 60 is double the exposure time of 125, four times the exposure of 250 and eight times that of 500, it is half of 30 and four times less than 15, etc. .