· Megapixels (MP): The first thing mentioned in digital camera ads is always the camera’s resolution in megapixels. Pixels are the tiny dots that digital pictures are made of; a megapixel equals 1 million pixels. The more megapixels, the more dots in the image. How many you really need depends on what size prints you plan to make. The rule of thumb is that you need 3 megapixels to make a decent 8 x10 print (the largest size that most computer printers can make). For 4×6 or 5×7 prints, email, and Web pages, 2 megapixels is more than enough. A higher-resolution image won’t necessarily make small pictures look any better!
· Zoom range. Most digital cameras come with a zoom feature that lets you change the image magnification, so you can zoom in on a distant object. For example a 3X zoom lets you increase the magnification 3 times. Zoom is especially good for outdoor, sports, and nature photography. “Optical zoom” is the only real zoom
· Automatic or manual exposure control. All digital cameras have automatic exposure control; that is, they change their lens opening and shutter speed automatically in varying light conditions. A good feature on some cameras is the “spot metering” mode, which automatically adjusts the exposure for the center of the frame only; this is good for “backlit” subjects (dark subjects in front of a brightly-lit background) that would otherwise be underexposed.
· Automatic or manual focus control. Some very simple cameras are preset to a fixed focus on a specified range, perhaps 6 feet to infinity. But most digital cameras have “autofocus”, which usually uses a spot in the exact center of the scene to automatically focus the camera’s lens. This works fine when there is something in the exact center of the scene that you want to be sharply focused.
· Removable storage. Different cameras use different systems for storing images. The most common system uses reusable “memory cards”, small removable cards that store your pictures electronically. Memory cards come in several different types (e.g. SD, XD, Memory Stick, etc), sizes, and speeds.
· Cost of required accessories. Many digital cameras are sold stripped-down, without accessories that you might eventually need. For example, extra batteries are essential. Some cameras are sold only with non-rechargeable batteries that drain very rapidly, so you may want to buy rechargeable ones and a battery charger.