• First things first: why do you want one?
• How digital cameras work
• Photo Terminology
• Camera features
• Storage
• Connectivity
• Power
• Image Compression
• Design
• Software
• Questions to ask the retailer

Photo Terminology

Resolution

One of the most critical ways to judge a digital camera's image performance is by its resolution. A camera's resolution is defined by multiplying the number of pixels on the sensors horizontally with those vertically - otherwise referred to as the pixel rating.

Pixels (short for picture element) are minuscule dots which, when put together, create the image that appears on a digital screen. The more of these pixels there are on the screen, the sharper the image created and the greater the flexibility when taking and printing your photos.

Typically, CCD resolution ranges from 4-megapixel (in lower-end products) to as much as 12 megapixels. This can also be represented as 2272 x 1704 pixels to 4288 x 2848 pixels.

Alongside these figures, several manufacturers use two terms to describe the camera's resolution: effective versus total resolution. The total resolution figure represents the total number of pixels on the CCD. Effective resolution represents the number of pixels which are used to produce the image. Not all of the pixels on the sensor are used in generating the image, partly because some pixels are used as part of the circuitry for calculating the levels of charge across the sensors, and also because the CCD or CMOS device can create picture degradation on the very edge of the device.

So, a digital camera with a total resolution of 2384x1734, for example, can only generate images with a maximum effective image resolution of 2272x1712. Therefore, the figure which accurately gauges the camera's resolution is the effective one.

If you intend to take pictures only to e-mail to friends or to print at snapshot size, a camera with a low resolution will do. Even so, more pixels give you greater flexibility - you can print sharper pictures at larger sizes, or crop small pieces out of pictures. Basically any reasonably good 5 megapixel model will produce more than adequate shots up to a print size of 6in x 8in or so, but for bigger enlargements or more creative work, you'll want a more advanced device.

Cameras on the higher end of the resolution scale will have a steeper price tag, though, so make sure you know what you want to use the digital camera for before buying.

Digital cameras will also come with a selection of resolution choices, which often confuses the user. Setting an image in a high or "fine" resolution will result in a better quality picture, but will inevitably take up more memory than an image set in a lower resolution mode.