When shopping for a digital camera, start by identifying your needs. Will you primarily be viewing your pictures on a computer screen or do you plan to make a lot of prints? Will you be using the camera for professional graphics work? Will you want a zoom lens? Are there specific features you require, such as macro ability or movie mode? Knowing what kind of photos you'll be taking most often will help you decide what resolution, storage type, power source, and other amenities you'll need. See the specific features below for more details.

The resolution you need depends on what you plan to do with your photos. If you just want to e-mail photos to your friends or put them on the Web, you may be happy with a low resolution such as 640 x 480. If you want to print your photos, however, plan on having at least 150 or more pixels per printed inch. If you try to print lower-resolution images at larger sizes, the results tend to look grainy, blurry or blocky. Most cameras also offer the option of taking lower-resolution photos so that you can fit more photos in the camera's memory.

Here's our approximate guide to maximum print size by resolution (based on prints at 150 pixels per printed inch): 0.3 Megapixels (640 x 480) = 4 x 3" print
1.2 Megapixels (1280 x 960) = 7 x 5" print
2 Megapixels (1600 x 1200) = 10 x 8" print
3.2 Megapixels (2048 x 1536) = 13.5 x 10" print
4 Megapixels (2288 x 1712) = 15 x 11" print
5 Megapixels (2500 x 2000) = 17 x 13" print
 

The image sensor in digital cameras is smaller than the surface of a 35 mm negative, so lenses on digital cameras tend to be much shorter than on traditional cameras. Look for the "35 mm equivalent" rating to get a better idea of a camera's range. Most fixed-length lenses on digital cameras fall somewhere between wide-angle and normal focal length. Many digital cameras now offer zoom lenses, which take you from wide-angle to telephoto. In addition to this optical zoom capability, some cameras provide digital zoom, which is nothing more than software in the camera that crops the edges off of your image and blows up the remaining information to the size of the original. While digital zoom adds extra close-up power, this comes at the expense of resolution. We recommend getting a camera with an optical zoom. Some cameras also have macro capability, which lets you focus very close and take pictures of small objects--useful for taking photos of flowers, jewellery and so on.

There are two types of zoom used on digital cameras--optical and digital--both of which are rated by how many times "larger" they can make a distant object. "3x optical, 5x digital" on a camera's specifications, for example, means that a camera's optical zoom can magnify by a factor of three, with the digital zoom providing a magnification of five--in combination providing a maximum theoretical magnification factor of fifteen times.

When using an optical zoom, the camera's lens does all the hard work, increasing or decreasing the apparent size of your subject in your picture in much the same way as a pair of binoculars. A digital zoom, on the other hand, is nothing more than software in the camera that crops the edges off of your image and blows up the remaining information to the size of the original. This method has limitations however, with the extra close-up power this provides coming at the expense of resolution. This can be a particular problem on cameras with a relatively small megapixel rating, as images can become slightly blocky and lacking in detail. We recommend getting a camera with an optical zoom, using this as your primary means of magnification and only resorting to the digital zoom when you require extra magnification, as this will help keep your pictures as crisp and sharp as possible.

Most cameras automatically determine the correct exposure for the lighting conditions. Sometimes, however, the scene will appear too dark or too washed-out. In these cases, it's handy to have a digital camera that offers manual exposure compensation, allowing you to set the exposure a few stops brighter or darker. A digital camera's ISO-equivalent rating lets you know how light sensitive it is; a camera rated ISO 100, for example, has about the same light sensitivity as a traditional film camera loaded with ISO 100 film. Higher ISO ratings mean the camera is more sensitive to light and can take pictures in darker settings.

Digital cameras work just like traditional cameras when it comes to aperture: the maximum aperture rating of a camera lets you know how much light it can let in. Aperture ratings represent ratios; the lower the aperture rating, the more light sensitive the camera is and the better it can take photos in low light.