Everything you need to know about digital photography

Choosing a Camera

Types of Camera     Camera Features     Zoom     Megapixels     Focus range
Scene modes     Image stabilisation     Sensitivity and ISO     Sensor size

Choosing photographic equipment can be a difficult job. There are so many brands and models to select from, it's sometimes overwhelming! However, by using our helpful guides you can make sure that you've considered the important factors and asked yourself the relevant questions before making your purchase.

Types of camera

Perhaps the first question to ask yourself when choosing a camera, is "where and when will I use it?" The best camera in the world won't take good pictures if it's been left at home because it's too big, or too valuable, or for some other reason. So you need to choose a camera that you will be comfortable carrying in those situations where you want to take photographs.

Compact cameras

For spontaneous photos taken on a whim, a digital compact camera or even a phone camera can be the perfect thing, easy to keep in a pocket and instantly available when you have the urge to take a photo. The trade-off with such a camera is typically in image quality and creative flexibility, although many higher-end compact cameras offer a degree of control over the settings used for shooting.

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At the other end of the spectrum is the DSLR (Digital Single Lens Reflex) camera, which will give you complete control over the settings if you so choose, will generally have a larger and higher quality image sensor, and will allow you to build up a collection of interchangeable lenses to produce the best quality photographs in any situation. This flexibility and quality comes at a price, however - not just for the camera itself, but also for the ancillary equipment that goes with it. And a DSLR is far less portable than a compact camera - but for quality and creative control it is unbeatable.

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Bridge cameras

A third alternative, midway between the compact cameras and DSLR, is the so-called bridge camera. This will typically have the look of a small DSLR, but will not have interchangeable lenses - instead offering a built-in lens with a wide zoom range. Usually a bridge camera will offer some level of control over exposure settings, although generally not to the same extent as with a DSLR. It will be considerably more portable than a DSLR, but less easy than a compact camera to slip into a shirt pocket.

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Camera Features

Once you have decided on the type of digital camera you are looking for, you will soon discover that there is a huge number of different models on the market - each offering slightly different sets of features and controls. Understanding these features and using the information to select the model that is right for you can be a difficult and time-consuming task - but the descriptions below should help you to come to a decision and with any luck you will end up with exactly the camera you want.

So, here are some of the technical features you should check for your camera before you buy it.

Zoom range

Zoom affects how much of a scene will be captured in your photograph. A zoom range of 5x means that at maximum zoom objects will appear 5 times larger than at minimum zoom. The actual size will depend on the focal length of the lens, which is normally expressed in millimetres - for example 33-165mm. Interpreting these values is made more complicated by the fact that the image size also depends on the size of the sensor inside the camera - so it is usual for the focal length to be expressed as a '35mm equivalent', which means that the numbers have been scaled as if the camera had a 35mm sensor. This allows different camera's zooms to be compared against each other.

So what do the number mean? Well, a focal length of 50mm used to be pretty much standard on 35mm film cameras, and captures an image that roughly corresponds with what's in clear view to the unaided eye. Shorter focal lengths are called 'wide angle' and will capture more of the scene, but with less detail of course. 30mm is fairly typical for the wide angle end of a zoom lens, but wider lenses can be found if you want to capture large buildings or expansive views in one shot. (Remember that these numbers are '35mm equivalent' values.)

The other end of the zoom range is called 'telephoto' and is used for photographing distant subjects - a friend across the street, a band on stage, a bird in a tree. The longer the focal length, the more magnification you will see. As usual, there is a tradeoff - at very high magnifications it becomes very hard to hold a camera steady enough to avoid blurred images, and the magnification also tends to exaggerate any shortcomings in the design of the lens which can produce coloured haloes around high-contrast subjects.

In summary: Choose a zoom range that you are likely to need, and don't be tempted to simply get the maximum zoom just for the sake of it - it may mean other compromises have been made in the lens design which will result in poorer image quality in general.


Camera manufacturers seem to strive to produce cameras with ever-higher megapixel ratings. In the early days of digital cameras, images were often limited in resolution - but nowadays that is seldom an issue, with most cameras offering over 10MP. So what are the tradeoffs? Should you automatically choose the highest megapixel rating? Here are some pros and cons of high megapixel cameras:



In summary: A high megapixel rating doesn't always imply a high quality image, and may actually make things worse. You should check for online sample photos to see what sort of quality images a camera actually produces with a variety of zoom settings.

Focus Range and Shooting Modes

All cameras will focus objects as far away as the horizon, but some cameras are better suited than others for close-ups. If you want to take artistic shots of individual flowers, for example, you should make sure that the camera has a macro setting - this will allow you to get really close and capture the finest details.

Most cameras also offer a range of predefined 'scene modes', which will automatically choose appropriate settings for the type of scene selected - for example, night photography, sunsets, portraits, sports, snow scenes, etc. Some cameras also have a mode in which the camera itself attempts to analyse the scene and choose a mode for you. Scene modes can be a quick way to get the camera ready to take the shot you want, although having a manual override for settings may be useful from time to time when the camera makes the wrong choice for you, or if its settings are not exactly as you would like them.

Image Stabilisation

When shooting in low light or at high zoom settings, it can be hard to hold the camera steady enough to get a photograph that isn't blurred by camera shake. Many modern cameras have built-in systems to help in this area, and some have more than one system. Stabilisation methods include:

There is not much difference in end result with the first two of these options, they are essentially different ways of achieving the same result. The last two methods are less expensive for manufacturers to implement, but will result in some delay between pressing the shutter button and the time the photo is actually taken - this may be an issue when shooting fast-moving subjects or sports. Note that none of these methods, except possibly the last, will reduce blur due to a moving subject.

With image stabilisation in a DSLR an additional consideration is cost of lenses. The first method, moving the sensor, is implemented entirely within the body of the camera and will work whatever lens is attached - whereas the second, adjusting the lens, is achieved by having special moveable elements within the lens itself. This will add to the cost of any stabilised lenses you buy for the camera.

Sensitivity and ISO rating

The ISO rating of a camera is an indication of how much light is needed to produce a well-exposed image. In the days of film cameras the ISO was a characteristic of the film that was loaded into the camera - a low ISO film would be used for bright, sunny conditions, and a high ISO film for indoor or overcast shooting. In a digital camera the sensor takes the place of the film roll, and clearly that cannot be changed to suit the lighting conditions! Instead, electronics inside the camera amplify the signal coming from the sensor under low light levels so as to bring it up to a more useful level. However this amplification also boosts any unwanted signals that may have been introduced by the sensor, and this unwanted information shows up as noise or graininess in the final image. Some sensors are better than others in terms of the amount of noise they produce, and so some cameras will produce better high ISO images than others. If you intend to shoot in relatively dim lighting - for example at concerts, or indoors without flash, then you should check the high ISO performance before choosing a camera - look for sample photos on the internet, and pay particular attention to the appearance of shadow areas.

Most cameras employ noise reduction techniques of one form or another, but these are inevitably a compromise, and frequently lead to pictures that look blocky or smeared.

Most cameras should perform adequately at ISO ranges from 100 to 800, with noise probably starting to become apparent as the sensitivity increases above 800.

Sensor size

Sensors sizes for digital cameras are normally quoted as a fractional number of inches - for historical reasons this is the size of a circle that contains the actual sensor with a significant border, so the actual sensitive area is markedly smaller than the dimension given. For example, a camera described as having a 1/3" sensor might actually have only a 6mm (approx 1/4") diagonal area actually collecting light. DSLR sensors may be specified in the same way, or they may be 'full-frame' - 43.3mm diagonal, the same size as a standard 35mm film negative - or some DSLR sensors are described as 'APS-C' which is a somewhat loosely defined size with a diagonal of around 28mm.

In general, a larger sensor area will gather more light and so be more sensitive, and capable of producing better (less grainy) pictures in a range of lighting conditions. However there is (as always) a tradeoff - larger sensors require lenses with correspondingly longer focal lengths to achieve the same field of view, and those lenses will be heavier and more expensive.

In summary: Subject to constraints of camera size, weight and cost, a rule of thumb is 'the larger the sensor the better.'