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What Is The Camera Shutter? How Does It Work?

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What Is The Camera Shutter? How Does It Work?

 

The shutter is the life partner of the aperture, and together they determine the amount of light that enters the camera.

In combination with the ISO, the shutter and aperture give us full control over the exposure of our photographs (this is what’s called the Exposure Triangle).

Why Is a Shutter Necessary?

The shutter helps us control the amount of light that hits the sensor by regulating the duration of the exposure. 

The aperture and the shutter work the same way – you can open the aperture and use a fast shutter speed or close the aperture and use a slow shutter speed to get a long exposure.

What Is the Shutter Speed?
What Is the Shutter Speed?

How Is The Shutter Constructed?

So, In the past, the shutter was mainly built from a circular system (like the pupil of an eye) inside the lens and it was completely closed to block the light from reaching the sensor. Today this type of shutter is mostly common in compact digital cameras, but it can still be found in niche cameras and medium format cameras.

In the past, in reflex cameras, the shutter was located right in front of the film and moved horizontally, until the vertical shutter system was developed.

But why does the vertical rather than horizontal better?

Because it’s shorter!

As mentioned, in modern reflex cameras the shutter is vertical and made of the most advanced materials such as metal or Kevlar, as opposed to cardboard or fabric in some of the old shutters.

The shutter has to be very durable and also very light so that it can withstand loads of very fast movement inside the camera.

The shutter is made of two curtains with one opening and exposing the sensor to the light and the other closing and blocking the light from reaching the sensor (Check out this link to see how the shutter work in a camera).

At high shutter speeds, while the first curtain is opening, the second is already starting to close, thus creating a small slit of light that moves along the sensor. This way, the advanced cameras today manage to reach speeds of up to 1/8000 with mechanical shutters on DSLR cameras and up to 1/64000 with electronic shutters on mirrorless cameras.

Some cameras have an independent electronic shutter or combined with a mechanical shutter. An electronic shutter simply defines the sampling duration of the light from the sensor by electronic means only.

What Is The Shutter Speed?

Shutter speed is measured in seconds or fractions of a second.

Any number that appears next to it with apostrophes, for example, “2 or “4, means an exposure of 2 seconds or 4 seconds respectively.

Any number that appears without commas expresses 1 divided by that number, for example, 250 represents 1/250 of a second and 4 represents 1/4 (a quarter of a second).

That is, during that period of time, the shutter will be open and the sensor will be exposed to the light entering through the shutter.

What Are The Shutter Stops?

As in the aperture, we use the term “stops”.

The stops of the shutter are:

BULB, “30, “15, “8, “4, “2, “1, 2, 4, 8, 15, 30, 60, 125, 250, 500, 1000, 2000, 4000, 8000

Pay attention to the numbers that appear with or without apostrophes (remember?)

As in the aperture, here too, the meaning of the stops is double or half the amount of light.

A shutter speed of “4 will let in twice the amount of light as a “2 (sounds logical right?), this is because the shutter will be open for twice as long and therefore twice as much light will enter.

On the other hand, be careful not to get confused because 1/500 will let in half as much light as 1/250 because it is half the exposure time.

In most cameras, the maximum exposure that the camera offers to the user is 30 seconds, but there are situations where a longer exposure is needed.

For this purpose, there is the Bulb mode or B. In this mode, pressing the shutter button will open the shutter, and releasing the button will close the shutter.

In such cases, it is better to use a remote control that connects to the camera with a cable, which allows you to set the shutter in an open position, so you don’t have to press the button for a long time with your finger.

A good example of using long exposure is in night sky photography.

Such exposure may continue for hours.

Using The Shutter Speed For Freezing Or Smearing

The shutter speed allows us to determine whether our image will come out “frozen”, that is, all the elements will come out completely sharp and without blurring (frozen water drops in the air for example) or with “smearing” which means an image in which there is blurring as a result of movement during the exposure.

Freezing – in order to freeze movement, you will need a shutter speed that will be higher than the movement speed in the image.

Using The Shutter Speed for Freezing
Labrador retreiver on grass playing fetch, shaking water off

This means that the exposure will be short enough so that nothing moves during it.

For example, to freeze the movement of a tennis racket, we would want an exposure of at least 1/1000 of a second, during which there would be no movement of the hand / racket / ball.

Smearing – to smear movement and get a blur as a result of movement, you will need a slower exposure than the movement speed.

Using The Shutter Speed for Smearing
Using The Shutter Speed for Smearing

For example, to smear walking motion you would want a shutter speed slower than 1/30, then you would see the motion of the legs smeared into the final image.

Motion Tracking Photography (Panning)

Panning, or “tracking camera”. The intention is to photograph at a slow shutter speed while following the movement of the photographing object with the camera and thus you finally get an image in which the subject will come out sharp and the background will appear blurred.

Motion Tracking Photography (Panning)
Motion Tracking Photography (Panning)

This photography technique is excellent for illustrating movement and creating dynamic and action-packed photos.

What is The Minimum Shutter Speed for Handheld Camera

We all tremble a bit all the time and of course also during the photo shoot.

In order to avoid the effect of these vibrations on the photograph, you can use a minimum shutter speed to “freeze” the image and the vibrations.

The rule of thumb for the minimum speed for handheld photography (without a tripod) is 1 divided by the focal length you are using at that moment.

This is a rule of thumb that expresses the fact that the longer the focal length and the narrower the angle of view of the lens, any slight shake of the hand will greatly affect the sharpness of the final image.

Meaning, a longer focal length will require a higher shutter speed to freeze the movement from the shakes of the photographer’s hands, while with a smaller focal length it will be possible to shoot with a relatively slow shutter speed.

For example, if you’re shooting at a focal length of 200mm, you’ll want a speed of at least 1/200 to avoid shaking.

At lower shutter speeds, you’ll want to use a tripod or some other support to get stability.

Shutter Lag

“Shutter Lag” is a term that expresses the delay between half-pressing the exposure (the shutter button) and focus until the shutter is pressed and the actual photograph is completed.

In compact cameras the lag is between 0.2 and 0.4 seconds, in digital reflex cameras, the lag is shortened to 0.04 seconds.

Of course, the shorter the lag, we can achieve higher levels of accuracy and timing in action-packed shots.

In cameras with a long shutter lag, we may miss many shots that depend on delicate and precise timing.

How Long Does The Shutter Hold?

Is there a limited lifespan for the shutter of the camera?

This is an excellent question.

In modern digital cameras, unlike film cameras, we are taking lots of pictures.

While in the past a film had 36 photos, today we are talking about hundreds or thousands of photos on one memory card!

The lifespan of the shutter has been extended according to the evolution of digital photography and today most camera shutters can last more than 120,000 shots and the more professional cameras, even over 300,000 shots.

OK,

And what happens when the shutter goes?

You just replace it and continue shooting.

What Is The Sync Speed?

The sync speed is the highest speed at which the camera can shoot with flash at normal exposure, this limitation is due to the way the shutter is constructed.

This speed is the maximum speed at which the sensor is still fully exposed to light at the same time, and above this speed, the sensor is exposed to light in a fragmented way, so a flash with a flash will show only a narrow band of light while the rest of the image will remain dark.

Which Shutter Speed Should You Choose?

Which Shutter Speed Should You Choose
Which Shutter Speed Should You Choose?

It depends on the amount of light available and the purpose of the photo.

When we are shooting in bright light conditions, we will need relatively high shutter speeds so that our image will not burn, and when shooting in low light conditions we will use lower shutter speeds.

If we want to freeze movement, we will try to achieve high shutter speeds by opening the aperture and increasing the sensitivity (ISO).

If we want to apply movement, we will need a low shutter speed (longer exposure) by closing the aperture and lowering the ISO sensitivity to the minimum.

If the shutter speed is still not slow enough, we can use an ND filter, which is a filter that is mounted on the lens (see the article on ND filters), which reduces the amount of light by several stops (depending on the type of filter) and allows us much longer exposures.

Summary

The shutter’s function is to control the amount of light that reaches the sensor.

Intelligent use of the shutter speed will allow us to apply or freeze the movement in the photo depending on the nature of the image we want to produce.

The modern shutter was developed after over a hundred years of research until it reached the level of complexity and precision of our days and with a reliability that allows even 300,000 photographs without breaking down.

Now you can start playing with the interrelationships of the aperture and the shutter.

Get to know your camera, take pictures, have fun, gain experience, and read more articles.

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AUTHOR
Hey there, my name is James and I am the creator and editor of this site. I have been photographing for the past 20 years and my mission is to simplify this misunderstood art of taking and processing photographs I love.

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