How many megapixels do I need?
Inexpensive digital cameras and devices which include camera options, such as mobile phones or MP3 players typically have 1-2 megapixels. It will be extremely difficult - if not impossible - to print high quality photos. However, you’ll do just fine if your plans only include emailing photos or posting them to web blogs or personal websites.
In general, these cameras are quite affordable and relatively sufficient for the average Joe. They’ll print optimal photos up to 5x7 or even 6x8.
You’ll get sharp images printing in this range, you can even get wonderful 8x10’s. However, if you are planning to crop and enlarge specific points in an image it might not be enough. For example, if you’ve taken a photo of a bear which turns out to look like a black spec in your image, cropping the bear and enlarging him to a reasonable size will result in a loss of quality and a grainy image.
7 Megapixels and Up
These cameras tend to be rather pricey, so unless you’re planning on printing poster-sized optimum quality photos, anything larger than 7 megapixels could just be throwing money down the drain. Also, keep in mind that more megapixels will require more memory. This means you’ll have to spend more on a larger memory card or settle for only being able to hold very few photos on a smaller card. And as for storage, larger pictures means more space is taken on your computer’s hard drive.