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Last updated on November 8th, 2020

Photography is much more than merely taking photos. 

It’s capturing memories, saving moments for years to come.

And because moments pass by quicker than a blink, photography demands precise control over light, which comes with the fundamental understanding of your camera. It is only then you will be able to save the essence of those moments.

Creating great images requires knowing the three pillars of exposure — aperture, shutter speed, and ISO.

While aperture affects the quantity of light entering the lens, the shutter speed decides the duration for which that light will be recorded. It can be for a millisecond or extend up to minutes.

Let’s learn about how the shutter inside a camera works and how its speed is measured, after which you can use it to create silky rivers and ribbon-like clouds in your photos.

How Does the Shutter Work?

In DSLR cameras, the image sensor is hidden behind the shutter, acting as a door to let in light. In turn, the shutter is hidden behind a mirror, which reflects the scene into the viewfinder.

There is obviously no mirror in mirrorless cameras since they use an electronic viewfinder instead of an optical one, but the shutter is still present — it’s an electronic shutter.

The role of the shutter begins when you click the ‘shutter button’ with your index finger. As soon as that button is pressed, the ‘door’ opens, and the sensor starts recording the photo.

When taking a picture, both the DSLR mirror and the shutter flip out of the way, so that the image sensor can record the light and capture the image. 

And this movement makes the trademark ‘click‘ sound of the camera. The shutter speed will decide how long this movement will last, and different speeds have different effects on the final image.

The shutter works through complicated mechanical and electronic controls because it needs to be very precise. And the delicate construction of a shutter means that the shutter mechanism of a camera can fail and stop working after several years.

This is why every shutter has an ‘actuation’ number — which is its life expectancy. It simply means the minimum number of times your shutter will open and close, although almost all modern cameras cross their count safely and continue working well.

Usually, DSLRs have an actuation of 100,000 — which is a hundred thousand images. You don’t need to worry about your camera failing you suddenly.

internal DSLR parts

What Does Shutter Speed Mean?

The word ‘speed’ here is slightly misleading. Shutter speed is really the length of time for which the shutter will remain open to let in light. Because it can range from a millisecond to minutes, the shutter speed is denoted in fractions of a second.

How exactly is that measured?

Those numbers like 1/250, 1/30, ¼, 2″ and so forth on your camera actually represent that duration; the ‘speed’ with which the door opens and shuts. Thus, ¼ implies that the shutter will remain open for a quarter of a second, while 1/1000 means that the shutter will stay open only for one-thousandth of a second.

Most cameras go up to 30″, which is a shutter speed of 30 seconds.

You need to set the ‘shutter speed’ to control how long the shutter will be kept out of the sensor’s way. Or use one of the camera’s automatic functions to calibrate the shutter speed for you. A faster speed means a shorter duration, which means that the shutter opens and closes quickly.

To make it clear, the shutter speed is a measurement of time; the duration for which light will be allowed to keep hitting the sensor. If your shutter speed is fast — something like 1/500 — your image will be captured in five-hundredth of a second.

shutter speed examples at different speeds illustration

What Are the Two Types of Shutter Mechanisms?

Old film cameras and all DSLRs use a ‘mechanical shutter.’

Like the name suggests, these shutters work by flipping