Our natural tendency is to buy a digital camera with the greatest resolution we can afford. The reasoning is, why get a 3 MP (megapixel) camera, when I can have a 5 MP camera? And to some extent, this makes sense.
However, before you buy that camera, consider your needs. How will you use the camera and the digital pictures it produces? If you will mostly share your pictures via e-mail or post them on your website, 5 MP is overkill? A 3 MP camera will provide all the resolution you need for e-mail and the Web, and even for the occasional 5” x 7” print.
Buying a camera with more resolution than you need has hidden costs. For example:
* All other things being equal, the higher the resolution, the higher the purchase price. You can afford a lot more features in a camera with lower resolution.
* Shooting higher resolution pictures requires larger memory cards to store the same number of pictures.
* The files from a 5 MP camera will require much more storage space than those from a 3 MP camera. That means they'll fill your hard drive twice as fast… or require twice as many CD's to store them.
If you're wondering just how much resolution you need (how many megapixels), here's an easy way to figure it out:
Find out the number of pixels there are on the camera's sensor array – both across and down. (This number will be in the manufacturer's specifications.) For example, Canon PowerShot S2 IS is a 5 MP camera. At its highest resolution, the CCD uses 2592 pixels x 1944 pixels.
Divide each number by 200. Using our Powershot S2 IS example, 2592 / 200 = 12.96 and 1944 / 200 = 9.72.
The resulting numbers tell you how large, in inches, a quality print you can get from the camera. So, the S2 IS should be able to provide you with good prints up to 10” x 13”.