Do you remember the term, "halftone"? A few years ago newspapers printed all photos in halftone, and if you looked very closely, you could see all the dots that made up the picture. The print process they used could not print a smooth gradation from black to white like a photograph does. So they used the halftone process to make the picture with small dots. Each dot could then be any variation of white to black. The dots in the dark part of the image were black and the dots that made up the lighest part of the image had no ink at all. Magazines have much better photos than newspapers because they use much smaller, and therefore many more dots. They also used different printing processes, inks, and smooth paper. Digital cameras have the same constraint as the newspaper presses - they can't record smooth gradations of color or tone because the camera sensor is also made up of dots called "pixels". "Pixel" is short for "picture element". However, digital cameras have so many more pixels than a newspaper press has dots that the human eye normally can't see individual pixels when printed or shown on a computer screen. A mega pixel is one million pixels. So think of a single pixel as one of those dots. The more you have, the better...sort of! Having a camera with a gazillion mega pixels can be like having a car with 800 horse power in Los Angeles traffic. Just as an 800 HP engine uses a lot of gas, cameras that produce 12 million pixels create very large files. Too large for sending via email without first resizing. They also take a lot more time to download from the camera and they fill up a hard drive like a fire hose fills a bath tub. If you want to take pictures and e-mail them to Grandma, or put them on your web site, or print them for the family album a 3 Mega pixel camera will do fine. Okay, so 3 Mega pixels is enough, so why would anybody pay extra for more? Let's suppose you take a picture with your 3 megapixel camera of your basketball star making the game-winning shot. Unless you are very close to the action, or you have a big expensive telephoto lens, your hero will only fill a small portion of the whole picture since your photo will contain about a third of the entire sports arena. So now you have a great shot of your hero...and the other players, and the 500 people in the stands! No problem because your camera came with software so you can crop the image and enlarge your star so he or she will fill most of the final image. With that software you are really trying to get a close up shot without a telephoto lens. THIS is when you will want LOTS of pixels! And here's why. Your hero's image was made up of, say 100,000 of your 3 million pixels in the original photo. Now, since you cropped away most all the pixels except those of your hero, you are asking those 100,000 pixels to fill the space previously filled with 3 million pixels because the finished print will still be, say, 4 x 6 inches. Your software actually preforms the required magic! Except now you still have 100,000 pixels, they just have tons of space between them. Your software knows this looks bad, so it guesses what color dots belong in those empty spaces and gives you enough pixels to make whatever size picture you want. But only 100,000 are "real" pixels which the camera recorded. When your print includes too many "guessed at" pixels, you get a very poor enlargment and a really bad print because printers need all the "real" pixels they can get. Printers are much more demanding than a computer screen. That is why a photograph can look great on the screen but be so bad when printed that you end up throwing it away. The moral of this story is if you are going to enlarge a small portion of your picture, or you plan on enlarging the original photo, (especially for printing) you really want a camera that produces as many pixels as you can afford. If not, you can just ignore the pixel-race of the camera manufacturers and concentrate on finding one with other features that are important to you.
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