On this page, we will introduce you to the basic technical aspects of using your digital camera. We will also explain how different settings of the various controls impact on the final picture. The topics discussed include:

  • Using the white balance setting
  • Getting the correct exposure
  • The effect different shutter speeds have on your pictures
  • How you can use different apertures to achieve particular results
  • Using different ISO settings and their limitations
  • Using different focal length settings and things you will need to watch
Using the white balance setting
All digital cameras come with an automatic white balance setting. This means that the camera automatically senses the type of light in the scene you are taking. The reason for this is that the colour temperature of light varies according to the time of day and the type of lighting. The performance of this feature varies from camera to camera. The best thing to do is experiment with yours to see what the results look like!

Many cameras also come with a range of different white balance settings to help with a standard range of lighting conditions. These can include:
  • normal daylight
  • outdoor shade
  • fluorescent lights
  • incandescent light (ordinary light bulbs)
Some cameras also have a preset setting where you can point the camera at a white or grey card that is in the same lighting as your subject and set your camera's white balance so that your subject appears to have the 'correct' colour balance. This is particularly useful if your subject is being lit by different lighting sources. It is possible to make corrections to the white balance of your photographs using computer software. However, it is probably less time consuming to use the correct white balance setting in the first place in order to save time later on.

The examples below show the results of different white balance settings for a particular camera in different lighting conditions. Remember that your camera may perform differently!

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Getting the correct exposure Lighting conditions can vary hugely when you are taking photographs. The good news is that modern cameras generally have very good metering systems for calculating the correct exposure and also have as much automation as you would want to help achieve well exposed pictures. The bad news is that digital cameras are rather less forgiving of exposure errors than cameras using print film. Therefore, you need to know what factors to take into consideration when deciding what will look best.

In order to get correctly exposed photographs (essentially photographs that are an accurate record of the scene), three main variables come into play:
  • Shutter speed: shutter speeds are typically expressed in seconds and fractions of a second and indicate how long the shutter remains open to admit light onto the camera's sensor.
  • Aperture: the camera lens aperture determines the quantity of light admitted onto the camera's sensor for the period of time that the shutter is open; the size of aperture is known as the f stop – lower numeric values mean that more light is admitted than with higher values
  • ISO (or sensitivity): most digital cameras have at least three settings. The ISO value determines how sensitive the camera's sensor is to incoming light with lower values meaning lower sensitivity.
Correct exposure for a particular scene will depend on the correct combination of shutter speed and aperture for any given ISO setting. Automatic exposure systems on modern cameras typically have a 'programme' mode that works it all out for you. However, there will inevitably be situations where that camera works out an exposure that while correct does not give you the results that you want. The next three sections explain why.

Shutter speeds
As mentioned above, shutter speeds are measured in seconds and fractions of a second. A typical digital camera may have a range of shutter speeds from 1 second (and perhaps as long as 30 seconds) to 1/1000th of a second (and perhaps as short as 1/4000th of a second). Naturally, when the shutter is open for longer, more light is allowed onto the camera's sensor. So, for example, a shutter speed setting of 1/60th of a second will admit twice as much light as a setting of 1/125th of a second.
There are two main factors you need to take into consideration:
  • The speed with which your subject is moving
  • The amount of camera movement when the picture is taken
Normally, but not always, we want to freeze movement in the subject and to do this we need to ensure that the camera has selected the correct shutter speed (either automatically or with some manual intervention by the photographer). The required shutter speed will depend on the speed with which the subject is moving, the distance the subject is from the camera and the direction of movement. Therefore, the required shutter speed will depend on the speed that the subject appears to be travelling in the viewfinder or on the camera's LCD screen.

The following examples show the effect of different shutter speeds for different subjects.

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Whether or not you want to freeze the movement in your subject, one thing you definitely want to avoid is the effect of camera shake. This occurs when the shutter speed of the camera is too slow to prevent involuntary movement of your hands causing unwanted blur in your photographs. The shutter speed you need to eliminate camera shake will vary from person to person. It will also vary depending on how you have used the zoom feature of your camera's lens. For a typical compact camera, when the lens is at its widest setting (i.e. when you can fit most in), the shutter speed needed to minimise the risk of camera shake will be around 1/30th or 1/40th of a second. When you zoom in to the narrowest telephoto setting, a shutter speed of around 1/125th or even 1/250th of a second may be needed to minimise camera shake. The good news that an increasing number of cameras are coming onto the market that feature image stabilisation or camera shake reduction technologies. This means that you can get away with slower shutter speeds. However, remember that these new technologies will not help to freeze the movement of your subject!

If your camera's programme exposure mode does not give you the shutter speed you want, you may be able to use the 'shutter priority' setting in order to set the shutter speed you need for the result you are trying to achieve. However, your ability to do this will also depend on whether it is possible for you camera to deliver a correctly exposed photograph through the adjustment of the aperture and/or ISO settings. This will be explained in more detail a little later.

The effect of different aperture settings
The aperture setting on your camera is used (in conjunction with the shutter speed and ISO settings) to help ensure that the right amount of light reaches your camera's sensor. However, there is a further important role that the aperture setting plays in you photographs - how much of your photograph is in focus. Aperture settings on a typical compact digital camera range from f2.8 (i.e. a large aperture letting in most light) to f8.0 (a small aperture letting in least light). The f stop scale can be confusing for beginners since it's not as obvious as using different shutter speeds to control the amount of light hitting the camera's sensor. The following table explains the relationship between different f stops and the amount of light falling on the sensor, beginning with f2 (a large aperture ):

 f2.8 admits half as much light as f2
 f4 admits half as much light as f2.8
 f5.6 admits half as much light as f4
 f8 admits half as much light as f5.6
 f11 admits half as much light as f8
 f16 admits half as much light as f11

There are also intermediate settings. Depending on your camera, these will be either increments of 1/3 or 1/2 of an f stop.

As mentioned above, the aperture setting has an important effect on the amount of the subject that is in focus (depth of field) at a given focusing distance. Larger apertures (lower numbers) result in a shallower depth of field than smaller apertures - in other words, less of your photograph is likely to be in focus. The depth of field will also depend on the distance that your subject is from the camera. The further away a subject is, the greater the depth of field for any given aperture. Therefore, if you are looking to isolate your main subject by having the rest of the photograph out of focus, you need to have your subject as close as possible at the same time as having a large aperture. The following examples show the effects of different aperture settings and distances of the subject from the camera at a range of different zoom settings.

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At this point it is worth mentioning an interesting characteristic of compact digital cameras when compared with Digital SLR (DSLR) cameras. Compact digital cameras have a much smaller sensor size than DSLRs. This means, in effect, that much more of the photograph will be in focus at a given subject distance. This means that it is going to be harder to compose pictures that have a mixture of in-focus subject and out of focus background elements. Whether this is important to you depends on the kind of pictures you like to take and for many people, having good sharpness across the whole of the image is often preferred.

Using different ISO settings
Your digital camera will typically have three or more ISO settings to control the sensitivity of the sensor. Typical ISO settings are 50, 80, 100, 200, 400 and 800. Some of the more recent cameras might also have 1600 and even 3200 settings as well. So what does all this mean?

An ISO setting of 50 means that your camera's sensor is set at the minimum sensitivity level. Each doubling of the ISO number doubles the sensitivity setting of the camera's sensor. By setting your camera to a higher setting, it becomes possible to use a faster shutter speed (perhaps to freeze subject movement or reduce the risk of camera shake) or to use a smaller aperture (to have more of the subject in focus), or a combination of the two.

You could be forgiven at this point for thinking that it's a good idea to set your camera to the highest ISO setting possible at all times! Unfortunately, higher ISO settings come at a price. The effect of increasing the camera's ISO setting is the production of a photograph with more 'noise' or graininess. This can be OK for smaller prints, but enlargements or selective prints from a portion of the picture can look very blotchy and lacking in detail. As a partial solution to this, some camera manufacturers incorporate 'noise reduction' technology in their cameras. This is fine as far as it goes, but the trade-off tends to be a reduction in detail on the photograph as the in-camera processing blurs the image to reduce the impact of sensor noise. The following examples show the results of higher ISO settings on the same image.

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Using different focal lengths
Compact digital cameras usually come with a built-in zoom lens. DSLRs differ in that they have lenses that can be detached from the camera body and be replaced with different ones for different requirements. Historically, many camera users for the last four or five decades have used cameras that take 35mm film. This means that we have become used to thinking in 35mm terms when describing the focal length of camera lenses. Actually the term that tends to be used these days is '35mm equivalent'. Therefore, from now on, we will refer to the focal length of different lens settings in terms of their 35mm equivalence. Part of the reason for doing this is that digital cameras have different sensor sizes and the actual focal length of a lens is linked to the sensor size. What is actually important in practical terms is the field of view that results from the different settings together with other effects of using different focal lengths. We will look at three broad settings: wide-angle, normal and telephoto.

Wide-angles
As the name suggests, a wide-angle setting has a wide field of view that means you can 'get more in' to your picture. In 35mm equivalence, the wide angle focal length begins at around 35mm and gives a field of view of about 62 degrees. A 28mm setting is wider still and offers a field of view of around 72 degrees. The 28mm (35mm camera equivalent) setting is typically the widest found on compact digital cameras with 35mm being the more usual widest setting.

For DSLRs, the kit lenses that normally come as part of the package usually have a widest setting of 28mm (equivalent) focal length. Wide angle lens settings are good for fitting in group scenes and landscapes and other scenes where you want to include as much as you can in the shot. A further effect of using wide-angle settings is that the depth of field is greater at any give focusing point. One final benefit is that wide-angle settings mean that you can get away with slower shutter speeds than at longer focal lengths. The downside of using wide-angle lenses is that they can introduce 'perspective distortion' when used to take close-up pictures. The effect is to exaggerate the parts of your subject that are nearest the camera and is particularly evident when taking pictures of people - as you can see from the examples!

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A further characteristic of wide-angle lenses is that on many cameras they suffer from 'barrel distortion'. This means that straight lines at the edges of the picture bow out towards the sides and in towards the centre of the picture at the corners. For general shooting, this is not a problem but pictures of buildings and horizon lines can look unnaturally curved. This kind of distortion can usually be fixed quite easily in photo editing software.

Normal focal length
This lens setting is called 'normal' because it corresponds to our normal field of view of about 45 degrees. It corresponds to a focal length setting of about 50mm. At this setting, your camera's lens is less likely to suffer from barrel distortion and perspective distortion effects are reduced, but not yet eliminated. In fact, before zoom lenses became the norm, cameras of all types used to come with a normal lens because they were cheap to manufacture and easier to design. At this focal length setting, you should be using a shutter speed of about 1/60th of second to minimise the risk of camera shake ( cameras with built in image stabilisation will permit a slower shutter speed - perhaps as low as 1/15th of a second - but there is no guarantee that your subject will not move!)

Telephoto settings
One of the attractions of compact cameras is that the lenses usually have a telephoto capability. This means that you can zoom in on your subject and isolate it from its surroundings. Cameras vary but the typical maximum telephoto setting is around 105mm with a field of view of about 23 degrees. Camera manufacturers are now producing compact digital cameras with even longer maximum focal lengths with 140mm or even 200mm becoming quite commonplace. Most camera manufacturers also produce at least one 'superzoom' model with focal lengths stretching to 350mm or even 450mm. At telephoto settings, the perspective distortion evident at wide-angle settings disappears. This means that you should consider these settings for portraits or other shots where perspective distortion may be objectionable. At telephoto settings, depth of field is reduced which then allows you to further isolate your subject from its background. The big down-side from using the telephoto setting is that you need faster shutter speeds to reduce the risk of blurring your photograph as a result of camera shake. At the 105mm setting, you will need a shutter speed setting of about 1/125th of a second (or around 1/30th of a second for a camera with image stabilisation).

Pulling it all together
Hopefully you will have seen that there is a relationship between your camera's shutter speed, aperture, ISO setting and the focal length of your lens. Correctly exposed photographs require the correct combination of shutter speed, aperture and ISO setting for the prevailing lighting conditions. The matrix (sometimes called 'pattern') metering systems in most digital cameras do a pretty good job of correctly calculating exposure. In 'programme' mode, both shutter speed and aperture are calculated automatically. Some cameras also offer scene modes. Usually these mean that the camera will attempt either to keep the shutter speed as fast as possible and the aperture as large as possible (e.g. to freeze motion, avoid camera shake or provide flattering backgrounds for portraits), or keep the aperture as small as possible (e.g. to maximise depth of field). Many cameras also offer 'aperture priority' and 'shutter speed' priority automatic modes so that you have more control over the final results by selecting appropriate shutter speeds or apertures. Finally, the most flexible cameras offer full manual control where you decide on the shutter speed and apertures

Some cameras will also automatically adjust the ISO setting in order to help minimise camera shake, but you need to be aware of the noise implications as mentioned above. Indeed, in low light situations, it will be impossible to take sharp photographs because even with your lens aperture wide open, the shutter speed will be too low to reduce the risk of camera shake.

Of course, if there is not enough light, you can always use your camera's built in flash. However, there are two things you need to be aware of. Firstly, the flash will have a limited range of perhaps up to around four meters (and usually less when using your camera's telephoto lens setting). Secondly, using the built in flash on many compact cameras can result your human subjects coming out with 'red-eye' due to the close proximity of the flash to the lens. Finally, your choice of focal length setting will influence how you might need to use different shutter speeds to minimise the risk of blurring from camera shake.

Before concluding this article, one more control on your camera is worth of mention: the quality and image size setting. Your digital camera is likely to have at least three different size settings and two or three quality settings. Larger image sizes and higher image quality settings will mean that your photographs will occupy more space on your camera's memory card. However, there are good reasons for choosing the highest quality and largest image size settings.

Firstly, larger image size settings allow both for bigger enlargements and also enable you to crop your images to produce selective prints. Secondly, lower quality settings, also reduce the potential for producing enlargements because less information is recorded. This also limits the size of prints you can produce to an acceptable quality. Given that memory cards are inexpensive, it is always a good idea to have several available in order to maximise your picture taking possibilities.