Shutter Speed - Exposure and Motion

Your camera has a shutter in front of the digital sensor. When you take a picture this shutter opens briefly to allow the light to fall on the sensor. This can happen very quickly, within 1/400th of a second, or very slowly, whole seconds. When Louis Daguerre took his first picture his shutter speed was 8 hours!

The poise, framing and composition all lead to the runners face and the determination shown on it.

From an artistic viewpoint shutter is really all about freezing motion. The faster the shutter, the more "frozen" the image.

For example your typical "frozen" sports shot would be of the athlete's expression while in action.

The motion blur in this image captures the joy and exuberance that a frozen shot would not.

But another way of conveying action would be to let some motion blur into the image.

Camera Shake

A fast shutter speed also prevents the image being blurred because you moved the camera while the picture was being taken.

Camera shake occurs because even tiny fractional movements of the camera can make a big difference. This effect is worse when using a long lens. This camera shake can come from natural body motion, breathing, heart beats and, of course, pressing the shutter.

As a rule of thumb you should probably aim for a shutter speed at least equal to the focal length of the lens. So with a 100mm lens you can probably manage 1/100th of a second. With a 400mm length you would need 1/400th of a second.

Avoiding Camera Shake

Of course if you have ways of keeping the camera more stable then you can use longer shutter speeds. The most obvious one is to put the camera on a tripod. But there are ways of making hand-held shots more stable.

Generally pull the hands and arms in tight, still your breathing, and press the shutter button gently.

Image Stabilisation

This can be a feature of your camera or your lens. Some manufacturers call it Vibration Reduction.

Essentially any slight camera motion is monitored and the focus automatically adjusted to compensate for your camera shake. This is a terrific feature and will often let you shoot at up to 2 stops slower than usual. So instead of a shot at 1/100th of a second you might be able take a shot at 1/25th of a second without getting noticeable camera shake.

It's not magic and won't always give you that benefit but it is normally very effective.

Managing Motion Blur

Motion blur is the shutter equivalent of focus. In other words if your subject moves while taking your shot you will get motion blur. Whether it is enough to stop a photograph being sharp and crisp depends on the speed of movement and the distance to the object.

The faster an object is moving the faster the shutter speed you need.

The closer an object is to the camera the faster the shutter speed you need.

You can photograph fast moving racing cars at slow shutter speeds providing they are at a distance. Similarly a slow moving person will look blurred if photographed close up.

Interactive Example - Human Speed

Move the slider left and right to see the effects of varying shutter speeds.

Although only moving at walking pace you can see the image is starting to deteriorate even at a shutter speed of 1/180th of a second and gets much worse at slower shutter speeds

At shutter speeds of 1/60th of a second motion blur is very obvious and you can treat this as a rule of thumb that at any distance 1/60th of a second will give motion blur.

Interactive Example - Fast Speed

Move the slider left and right to see the effects of varying shutter speeds.

You can see that at faster shutter speeds - 1/4000th of a second there is almost no motion blur in the fan at all. As shutter speeds get slower some motion blur starts to appear. And of course as shutter speeds get really slow then the fan moves so far during the exposure that it is not visible at all.

What Shutter Speed Should I Choose?

This handy guide - which is included in the bonus awards for this section - gives you a quick reference to the typical shutter speeds you might use for different photographic situations.

The Peak Action

When freezing action, the trick is to catch EXACTLY the right moment, called "Peak Action". For example, capturing a dancer as she seems to hang motionless in the air.

Taking the shot just slightly too early or too late will lose that moment of peak action.

If you can see the moment, then you are shooting too late. You have to anticipate the moment and be pressing the shutter button in time with action.

Dancer at the moment of "Peak Action"

You can try the "spray and pray" method of taking many, many shots in a very short time and hoping. I can tell you now, that will let you down more often than not.

To prepare for this kind of shot you need to pay attention to the movement and be in sync with the subject.

Camera Setup for Peak Action

You can prepare your camera in advance to give you a better chance. Firstly set your camera to the shutter speed you think you will need. If needs be try a couple of test shots.

With the shutter speed set, what aperture will you need for a correctly exposed image? If it has a very wide aperture (below f8 or more) then you may want to increase your ISO to compensate. You do not need to preset your aperture, but you do need it to be in the right range for your photograph.

Next you probably want to pre-focus. If the action is very fast your camera focus will not keep up. So you pick a point and use manual focus to fix on that point.

Then as your subject moves to that point, or reaches the "peak action" moment your camera is ready to shoot with no delay.

A story about city life - rushing cars in a grey city.

Slow Shutter Speed

Using slower shutter speeds to deliberately catch motion blur can give images a more artistic, impressionist quality. The aim is not to capture the detail of a scene, but the sense and feel of a scene.

For example if you freeze the motion of water in rapids then it looks unexciting and muddy. But if you let in some motion blur for a "milky" water effect then the photograph properly invokes the sense of water.

You would capture a shot like this by positioning your camera on a tripod with a shutter speed of anywhere from half a second to 5 or 10 seconds or even more.

The slow shutter has really caught the sense of flowing water that freezing the shot would not have done.

Of course there are more extreme examples of motion blur such as shooting light trails or stars at night. You will look at these topics in more detail later.

Panning and Motion Blur

You've captured this wonderful picture of a racing car; everything is perfectly frozen in time. But.... But it might as well have been parked, not doing 200 miles an hour. This is because the spinning wheels look completely still and the background is static and crisp. What you need to do is create the sense of motion by having the background blurred.

A nice crisp capture, no spinning wheels.

panning racing car

The trick is to use a slower shutter speed and track your camera with your subject. This way the car remains in the same place in the photograph but the background sweeps past. This technique is called "panning".

This is a technique that needs practice. You must pan your camera with your subject all the way through. You must keep your movement exactly in time with the movement of the car. As you are panning with the car you press the shutter button - being very careful not to jiggle the camera - and keep panning the camera until the shutter closes.

You know when you get it right because the car is sharp, the turning wheels are blurred and the background streaks behind the car.

Catching Light Trails

To photograph light trails (for example, cars at night) you need exposures measured in seconds and a dark place to shoot.

Lock your camera onto a tripod. Set your aperture to a small as possible (higher f-stop). Set a shutter speed of 10 seconds. Take a test shot of moving lights. From here you will see whether the trails are too long or too short. Adjust the shutter speed to get the look you want.

A 40 second exposure capturing these lovely curving lights.

Bulb Setting

Your camera will have a limit on how slow a shutter speed you can set, typically 30 seconds. If you want to take photographs longer than that you need to use the "Bulb" setting. In this mode the shutter stays open as long as you have your finger on the shutter button.

External Shutter Release

Of course you don't normally want to sit like a lemon with your finger down so bulb shots are usually made with an external release.

The external release has a locking mechanism that lets you lock the shutter open. It will stay open until you release the lock. No need to keep your finger on the button.

You would use this for shooting star trails over many minutes.

By using an external release you also reduce the camera shake caused by pressing the shutter button.

More advanced external release products have interval timers. This lets you take a series of pictures at pre-determined intervals. This can let you create time lapse sequence for example.

Interval Timers

An interval timer lets you set a camera to take a series of photographs at regular intervals. The intervals can be from several per second to one every day depending on the timer.

You are also able to set a maximum number of pictures as well. So you can ask for 60 pictures to be taken, one every minute, for the next hour.

Wireless Shutter Release

While most external units use a cable, there are means of using a wireless radio trigger instead. Most useful with wildlife where you can leave the camera in place and watch the animals from a safe distance. These are also often used for sports photography; a camera might be left behind a goal mouth for example.

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Assignment: Photograph Moving Objects

The assignment for this section is to photograph some moving objects. The easiest thing to find will be moving cars.

Find somewhere where you can see a road, but do not get too close. Make sure you are safe.

1) Take pictures with a fast shutter speed (1/500th of a second or faster) - look at how it freezes motion

2) Take pictures with a slow shutter speed (1/50th of a second or slower) - look at how it is blurred

3) Get closer to the cars and repeat - how does this change the amount of blur?

4) Practice your panning technique at 1/50th of a second to get a blurred background but sharp car.