Intermediate Tutorial 1

Shutter Speed is a useful tool for the creative photographer. Manual adjustment of your Shutter allows precise control of the exposure to achieve specific effects. In this tutorial, we look at the techniques involved and the pitfalls to avoid.

1

An Introduction to Shutter Speed

What is a shutter?

The Shutter is like a curtain inside your camera – one of the elements controlling how much light is exposed to the sensor in order to capture an image. As with a window, if you draw a curtain across it then the light is blocked. With no light landing on your camera’s sensor, no image can be created. Opening the Shutter allows light in – and that is captured by the image sensor, along with an image of the subject reflecting it. The brief moment the Shutter is open – when you press the shutter release button – is called the ‘exposure’ time.

The camera’s Auto function – or you, manually – can control how long the Shutter opens by setting the Shutter Speed. The scale for shutter speed is presented in seconds and fractions of a second, e.g. 2 seconds, 1 second, 1⁄2, 1⁄4, 8 (=1/8th), 15 (= 1/15th), 30, 60, 125, 250, 500 etc.
 The speed, or amount of time the Shutter is open, determines two things in your picture: how bright or dark the image will be, and the position of the subject captured on the sensor.

So firstly, the light-sensitive cells on the image sensor turn absorbed light into electrical signals at an incredibly fast speed. But if the Shutter is not open long enough, not enough light is absorbed and the resulting picture will be too dark (this is called underexposure).

On the other hand, if the Shutter is open too long, too much light is absorbed and the picture becomes too bright (overexposure).

If we control the speed of the Shutter correctly, the picture will be perfectly exposed – neither too dark nor too light.

Exposure too dark

1/80th sec. exposure = too fast/too dark

Exposure too bright

1⁄4 sec. exposure = too slow/too light

Correct Exposure

1/6th sec. exposure = Just right


Motion Blur

Looking at the second point, light is reflected by the subject into the lens and its image is captured. As long as the subject or the camera doesn’t move, the image will be captured at one position on the sensor – nice and sharp. However, if either the subject or camera moves, the image will be captured with movement, resulting in a blur.

The effect of subject movement is called ‘motion blur’, while a blurry image caused by camera movement is due to ‘camera shake’.
 In either case, in order for a subject to be captured without blur, the Shutter Speed needs to be set very fast (short exposure time) – movement is not recorded because the image is captured in a fraction of a second, too fast for motion to be detected.

Sometimes, motion blur is intentionally used – for instance, to emphasise movement or speed.

The two images below are the same subject shot from the same angle, but by using different Shutter Speeds, you can see that two very different images are created. The short exposure time in the first picture means individual droplets of water can clearly be seen breaking over the rocks. Whereas the longer exposure time in the second picture gives the water a silky blurred effect.

Fast Shutter Water

Shutter Speed: 1/250th sec

Slow Shutter Water

Shutter Speed: 1⁄4 sec

As mentioned earlier, the shutter is only one element that can affect exposure. The other elements are Aperture and ISO (sensitivity). In order for an image to be correctly exposed, they all need to be working in harmony – called the ‘exposure triangle’. Aperture and ISO are covered in more detail in other tutorials, but you need to be aware that when changing any one of them, you may need to adjust either of the other two to compensate and expose correctly.

Luckily, a digital camera’s ‘auto mode’ takes care of exposure automatically and even a beginner can take pictures that are exposed correctly the majority of the time. But what if we want to start experimenting with shutter speeds in order to create a dramatic shot? This is where the ‘Shutter priority’ mode comes in.


Shutter Priority

Shooting mode PASM dial S

Set the camera’s mode dial to position ‘S’

Advanced cameras that offer manual controls over exposure usually have a dial with ‘PASM’ shooting modes included – sometimes seen as PAvTvM.

By selecting ‘S’ or Shutter Priority on the dial, the camera will allow a Shutter Speed to be selected manually, but will still control the exposure automatically by adjusting the Aperture or ISO (or both) in relation to the speed selected and the level of available light detected by the camera.

This gives the user flexibility to choose a Shutter Speed for a desired effect, while still maintaining correct exposure.

Of course, depending on the lens Aperture and ambient light level, there are limitations to the exposure settings a camera can make. Where possible, use the on-screen display as a guide to the range of Shutter Speeds available for each shooting scenario.

Shutter Priority

In this example, Shutter Speed is set to 1/60th sec, which is in the ‘safe area’ for a good exposure.

On the LUMIX G cameras, a guide will appear as a bar on the display when you adjust Shutter Speed. The bar shows the range of speeds with a red area that, if selected, will give an incorrect exposure.

As long as you select a speed that is not in the red, the camera will be able to select an Aperture or ISO setting to result in a good exposure.

 


What shutter speed should I use?

A very good question! Although it depends on the subject you’re shooting and the effect you’re trying to achieve. However, there is a rule of thumb to help you avoid blur when shooting handheld.

Select a Shutter Speed at least equal to the focal length of the lens. This means that if you’re shooting at 100mm you should select at least 1/100th sec, 250mm = 1/250th sec etc. If you want to shoot slower than this, you require a very steady hand – or better still, a tripod.

For creative use, the speed you choose depends on whether you want to create a sharp ‘frozen movement’ picture using a very fast Shutter, i.e. short exposure – such as this:

High-Speed

Pacu Jawi cow racing in Sumatra, Shutter Speed = 1/1,000th sec.

Or you could go for a slow shutter/long exposure – like this:

 

Long Exposure

Bus passing The Randolph Hotel, Oxford, Shutter Speed = 20 secs.

P1010951

For handheld shots with exposure time longer than about 1/30th sec, there’s a risk of camera shake. If the camera or lens offers image stabilisation, activating it will increase this to about 1/20th sec, so for shots requiring a longer exposure it’s important to place the camera somewhere rigid, or use a tripod.

In some cases you may want to take a shot with an exposure time longer than 60 secs – like this amazing car lights trailing shot on the right.

Most cameras offer up to 60 secs on the Shutter Speed settings, but if you want to expose for longer you need a model with ‘Bulb’ mode, for which you normally have to set the camera to ‘Full Manual’ exposure (‘M’ setting). Bulb mode allows you to keep the shutter open for as long as the shutter button is pressed. It’s useful to use an accessory called a shutter release cable for this type of exposure, otherwise it is difficult to keep the camera steady with your finger pressed on the button that long.

So we have learned that shutter speed can be used to lighten or darken an image, reduce blur caused by camera shake/subject movement or intentionally create blur/freeze motion for creative effect.


The LUMIX Advantage

LUMIX G cameras include a useful ‘Shutter Effect Preview’ function that allows you to see how the image will look as you change Shutter Speed, but before you take the shot.

Even more useful, the Preview option can be allocated to one of the function buttons – so you can set it to your preferred position.

Shooting Exercise

So, having learnt how to use your camera’s Shutter Speed to create different effects, let’s try an experiment. Find a water feature where you can try out different Shutter Speeds. A slow-running stream or waterfall is ideal for practising long exposure, ‘silky veil’ effects.
Choose an overcast day or somewhere not too bright, as you may need to use speeds as low as 1⁄4 sec. For the high-speed ‘frozen droplets’ effect, a fountain, weir or leaky lock gates are great!

Choose a bright sunny day to allow a shutter speed faster than 1/500th sec. (A word of caution: take great care when shooting near water; never take risks that may cause injury or endanger life.)

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Written by Steve Lucas for Panasonic ©