Technology buyers' guide: digital cameras

What are megapixels, and why are they important?

Digital still camera resolution is measured in megapixels — 1 megapixel = 1 million pixels on the image sensor of the camera. Capturing more pixels of image data results in higher resolution images (and larger file sizes).

Higher resolution is not always needed, however, depending upon how you want to use your images.

camera resolution	photo quality	very good quality up to
2 megapixels	up to 5 x 7" prints	8 x 10" prints
4 megapixels	up to 8 x 10" prints	11 x 14" prints
6 megapixels	up to 11 x 14" prints	16 x 20" prints

Point-and-shoot cameras

This type of camera is generally small, compact, with a built-in zoom lens and flash, but some offer a surprising array of automatic and manual controls. Optical zoom refers to the range from wide angle to telephoto the lens itself provides, and is usually described by a ratio (like 3:1 or 4:1) or compared to a 35mm camera lens(such as 35-105mm). The higher this ratio, the greater the change from wide to telephoto. Digital zoom enlarges the pixels electronically to 'zoom in' to a portion of the image. Our suggestion: don't use digital zoom — you can always crop the image later and get the same results.

Digital SLR (single-lens-reflex) cameras

Similar to a film SLR, these cameras allow you to change lenses to suit your needs. Most also have larger image sensors than the small cameras, which capture higher resolutions and smoother color graduations.

Image quality and file sizes

Most cameras offer controls over resolution and file compression settings. For example, a camera with a maximum resolution of 2592 horizontal pixels by 1944 vertical pixels (5 megapixel resolution) may also offer several lower resolutions to choose from, such as 640 x 480 pixels. Lower resolution means smaller files, so you can fit more images on your memory card. Our suggestion: use the highest resolution the camera offers, and buy a larger (or an extra) memory card.

Another control may be called Image Quality with settings such as Basic, Normal, or Fine. This determines how much JPEG compression is applied to the image to reduce the file size. Greater compression delivers lower image quality. Our suggestion: Use the highest JPEG quality setting.

Some cameras also offer a TIFF or RAW image quality setting, which will save uncompressed images for maximum quality. Serious photographers will want the additional quality and control you can get with a RAW image, and will be willing to deal with the larger file size and increased processing time involved.

For more information

Many online resources are available to help you decide on a camera. Here are two we like (each of these links will open in a new window):