Digital cameras have revolutionised photography, making it quicker, simpler, and cheaper to take great photos. They have all but replaced film cameras, and are the standard choice of most amateurs and professionals.
Choosing a digital camera can be difficult because there's such a wide range of types, makes, and models available. You need to consider the subjects you'll be photographing, the level of control you want over your camera's settings, and your budget.
This guide aims to explain the various types of camera available, and explain their most important features, so that you can make an informed decision and choose a digital camera which suits your specific needs.
Types of Digital Camera
Digital cameras come in many shapes and sizes, but can be roughly grouped into the following types:
Compact Digital Cameras
A compact digital camera (sometimes called a "point and shoot" camera) is designed to be as small and portable as possible. They are slim enough to slip into a pocket or bag, making them perfect for when you're out and about and want to get some great photos without the inconvenience of carrying a large camera around.
Although they don't offer the same image quality or level of control as more advanced cameras, digital compacts are an excellent choice for people who just want to snap away with minimal fuss.
A digital SLR (or "DSLR" for short) is a more advanced type of camera which offers the ultimate in digital picture quality, greater control over camera settings, and interchangeable lenses. They work in much the same way as traditional 35mm film SLRs, but use a digital sensor rather than film, greatly reducing or even eliminating processing costs.
DSLRs are the choice of professionals and serious amateurs who want the added versatility and control over settings such as aperture, shutter speed, and ISO sensitivity. As a result of this complexity they are the more expensive, larger, and heavier than compacts.
A digital bridge camera fills the gap between point and shoot cameras and DSLRs. They are very similar in appearance to a digital SLR, but lack some important features such an optical viewfinder and interchangeable lenses. However, the majority still offer a high level of control over camera settings, much like an SLR.
Bridge cameras can be a good choice for people who have reached the limits of a compact camera, but still want something which is relatively easy to operate. However, the growing number of cheap, entry-level digital SLRs is making bridge cameras increasingly redundant.
Interchangeable Lens Cameras
A recent addition to the digital camera market is the interchangeable lens camera. These fill the same gap as bridge cameras, offering something in between a point and shoot and a digital SLR. However, they offer something very different, with small, compact-like bodies and interchangeable SLR-like lenses rather the bridge cameras' large, SLR-like bodies and fixed lenses.
Interchangeable lens cameras offer an excellent alternative to entry-level DSLRs, with similar picture quality but much smaller bodies. The most popular type are Micro Four Thirds cameras, which use a universal lens mount to ensure all lenses are compatible with all cameras.
A digital back is a piece of equipment that contains a digital sensor, and attaches to the back of a film camera to give it digital capabilities. They are used on cameras which don't have a digital equivalent, or where there are very few digital models available, such as medium-format and large-format cameras.
Digital backs are very specialist pieces of equipment, and most photographers won't need to use them, but they are very popular in certain types of photography. They also tend to be very expensive, costing several thousand dollars.
Image Resolution and Quality
Probably the most talked-about feature of a digital camera is its resolution, usually expressed as the number of megapixels (MP) its sensor will capture. Most modern compact cameras will capture at least 5MP, with top-of-the-range digital SLRs having a resolution of 20 megapixels or more.
A common misconception is that a higher number of pixels indicates better image quality, but in fact this isn't the case. For a given sensor size, the more pixels it captures, the lower quality each pixel will be. However, because of the higher resolution, each pixel also takes up less space when the image is displayed a a particular size.
These conflicting factors cancel each other out, meaning that a 5MP camera will produce just as good a photo as a 10MP when their images are printed at the same size. The take-home message is this: when comparing digital cameras, look at the sensor size rather than the image resolution.
Sensor Type and Size
Digital cameras use an image sensor to capturing images. This acts much like the film in a traditional camera, but instead converts light into a digital picture which can then be stored on a memory card.
There are two main types of digital camera sensor - CCD (charge couple device) and CMOS (complementary metal oxide semiconductor). There are slight differences in the way these create a digital signal, but they produce images which are very similar in quality, so it doesn't matter which your camera uses.
One aspect of the sensor which is important is its size. A larger sensor will capture a better quality image, with less noise and greater detail. Sensor sizes range from around 1/2.5" in digital compacts up to 35mm for "full frame" digital SLRs.
As you might expect, a larger sensor is more expensive to produce, so you'll pay more for a camera which uses one. However, the improvement in picture quality means that it can often be worthwhile.
LCD Screen and Viewfinder
A camera's LCD screen allows you to view the images you've taken, adjust camera settings, and navigate menus. As well as this, almost all digital compacts, and some DSLRs, offer a "live view" mode, where you can use the LCD screen as a viewfinder, to frame your photo before pressing the shutter button.
In general, a bigger LCD screen with a higher resolution is better, as it will allow you to see your images and read menu options more clearly. Most modern cameras use a roughly 3 inch screen, which is more than sufficient.
As well as an LCD screen, some cameras have an optical viewfinder for lining up your shots. These are particularly common on digital SLRs, which generally don't have a live view mode. The best types of viewfinder are those that provide a "through the lens" (TTL) view, showing exactly what the camera will capture. Other cameras use a separate viewfinder which sees a slightly different image from what the camera will capture.
For cameras with built-in lenses, such as digital compacts and bridge cameras, the lens's zoom level is crucial in determining how well you'll be able to photograph distant subjects. A typical compact camera will have a zoom level of around 5 times ("5x"), while bridge cameras can extend as far as 24x.
In general, a higher zoom level is preferable, but it's also important to look at the lens's focal length range to make sure it can also cover a suitable wide angle at its widest setting - this is useful for photographing interiors and large, nearby subjects such as buildings.
There are two types of zoom - optical and digital. Optical zoom uses the lens's optics to enlarge the scene, maintaining a high quality picture. Digital zoom simply enlarges the image to give the impression of zooming in further. This degrades the image quality and decreases the effective resolution. When comparing cameras, make sure you are comparing optical zoom levels; digital zoom is essentially irrelevant.
Digital cameras with interchangeable lenses (including DSLRs) don't have such an extreme zoom range. This is because their lenses can be swapped, so they tend to choose higher quality optics over zoom capability.
Some digital cameras use image stabilisation to help you get a sharp photo with minimal blurring. This can be useful in situations where you are forced to use a slow shutter speed and can't use a tripod or other support, and can allow you to use a shutter speed up to 16 times slower than without image stabilisation.
Optical image stabilisation works by adjusting either a floating lens element or the image sensor to compensate for camera movement. This is better than digital image stabilisation, which uses software processing to even out shakes, but which cannot eliminate motion blur.
An increasingly popular function on digital cameras is "burst mode", where holding the shutter button down provides continuous shooting, capturing several photos one after the other. This mode is great for capturing fast-moving action or scenes where your subject is moving. It is typically only found on digital SLRs, although some manufacturers are beginning to add it to their compacts as well.
Burst mode is measured by two numbers. The first is the number of frames per second that it can capture, typically around 3 or 4 fps. The second is the maximum number of shots it can take in a row, usually at least 15 for an entry-level camera, with more expensive ones being able to shoot until the memory card is full.
Many digital compacts offer a video shooting mode. Originally this was just a gimmick, offering VGA resolution, low frame rates, and poor sound quality. However, over recent years it has become increasingly popular, and many cameras now offer full 1080p HD video recording. This feature is also making its way into some DSLRs.
Although the quality isn't as good as you'd get from a dedicated video camera, the results are still highly impressive, certainly good enough for the occasional home video. When buying a camera, you should still use its still picture quality as the main criteria, but video capture can be a nice bonus.
Digital cameras use two main file formats for storing pictures - JPEG and RAW. JPEG is excellent for storing high-quality images while keeping file sizes low (typically around 3MB). This format is more than sufficient for most people, and means you can fit more photos on your memory card.
As well as JPEG, digital SLRs can also shoot RAW images. These are uncompressed files, and store a greater level of detail than JPEGs, making them ideal for professionals who need very high-quality images which they can edit and enlarge. However, RAW files are much larger, meaning you can't fit so many on your memory card. As a guide, RAW file sizes are roughly equal to the image resolution, so a 12MP image will take up around 12MB.
Memory and Storage
A typical digital camera may include a small amount of internal memory, although this is usually only enough to store a handful of photos. To really make the most of your camera, you'll need to buy a memory card to go with it.
There are many different types of memory card, with Secure Digital (SD), CompactFlash (CF), and Sony Memory Stick being the most popular. They all do the same job, so don't worry which type your camera uses, just be sure to get one that matches. SD cards tend to be slightly cheaper than the other two, but prices are so low that it really doesn't make any practical difference.
Buying a Digital Camera
The first thing to decide is what type of camera you want. If you've been involved in photography for a while then you should have a good idea of what you need, and some sort of interchangeable lens camera will probably offer you the greatest control and versatility. If you are new to photography, or just want something to capture simple snapshots, then a digital compact or bridge camera will be more suitable.
Next, visit a store and try out some of their most popular models. See how they feel in your hand, and how easily they fit into your pocket if that's important to you. Test the lens's capabilities at its widest and most telephoto extents to see if it covers enough of a range for the subjects you typically photograph.
If possible, take some test photos with each camera, and take them home with you on a memory card, USB stick, or CD. You can then examine them in detail at home, comparing the image quality, noise, and colour reproduction to see which you like best.
Once you've narrowed your selection down to a handful of models, check online review sites to see what other people are saying, and to see if they recommend any alternatives.
Finally, you can shop around to find the best prices and look for special offers and deals which might sway your decision. Great places to start are Amazon and Adorama, two online stores which offer an excellent range of stock, unbeatable prices, and great customer service.
Cover image by Paul Reynolds.