Following are the major features and some caveats of digital cameras. See digital camera, photo sharing site and film camera. Resolution in Megapixels The number of pixels determines the maximum size of the resulting image and its sharpness, especially when printed. The higher the resolution to start, the better the results. You can easily reduce a high-resolution image to low resolution in the computer, but you cannot go from low to high. The bottom line: know the destination of your images. See megapixel. Minimum Destination Megapixels website images 1 MP Computer screen 2 MP 3x5 and 4x6 prints 2 MP 8x10 print 4 MP 11x14 print 6 MP 16x20 print 12 MP User Interface Nothing is more critical to photographers than the feel of their cameras. Because it uses a combination of physical buttons and on-screen menus, a digital camera's interface can be more daunting than that of a desktop computer. At the very least, spend some time in the store reviewing the basics. If at all possible, borrow the camera from a friend for a photo session. Optical and Electronics Quality The optical quality of the camera's lens greatly contributes to picture quality. In addition, the color and geometric accuracy of the pixels in the CCD or CMOS sensor combined with the camera's internal processing circuits make all the difference. Specifications on paper are not enough, and reviews from photographic websites are very valuable. Optical vs. Digital (Interpolated) Zoom The optical zoom is the real resolution of the lenses. The digital zoom is an interpolated resolution computed by software. The higher the optical number, the better. A 10x optical is far superior to a 10x digital (see optical zoom). Storage Media SD Cards, CompactFlash and Memory Sticks are the "digital film," but no matter which type the camera uses, the one that comes with the camera is typically undersized. Plan on purchasing a larger one when you buy the camera (see flash memory). Data Transfer Digital cameras come with a USB cable for transfer directly to the computer, and many computers come with one or more memory card slots. Printers may also come with card slots, allowing you to print your photos without using the computer at all. Wi-Fi is also available on some cameras. Battery Duration Digital cameras use either rechargeable or standard AA batteries. It can take an hour or more to recharge a battery, so having an extra, fully charged battery is recommended. AA batteries can be purchased anywhere, and rechargeable AA's can also be used. Interchangeable Lenses Digital SLR (single lens reflex) cameras are the digital counterparts of their analog predecessors and may use the same removable lenses that you already own. However, the sensor chip may be smaller in size than a 35mm frame, which means your 28mm wide angle lens might function like a 42mm lens. Lenses made specifically for the digital SLR do not have this focal length mismatch. See DSLR. LCD Screen and Viewfinder Small, point-and-shoot cameras use a "live preview" LCD screen to take pictures and display the stored images. Digital SLRs have a traditional viewfinder that you press your eye against for taking pictures and mostly use the LCD as a monitor to show the results. The larger the LCD screen, the more the camera serves as a convenient playback device. The viewfinder has always been effective for taking pictures, because pressing the camera against the eye actually steadies it. It also helps the photographer frame the picture. In addition, bright sunlight can wash out an LCD, making it difficult to see the image. As a result, some point-and-shoot cameras also include a viewfinder. See viewfinder.