Just like 35mm cameras need traditional "roll film", digital cameras need "digital film" memory cards to store pictures. Digital film comes in a number of formats, some more durable than others. The most popular formats are CompactFlash and Secure Digital (SD Card). When choosing a digital camera, you should consider the format of digital film that a camera uses.

Some formats, such as CompactFlash, allow additional features to be built into the memory card. For example, Lexar CompactFlash is speed rated to provide users with the minimum sustained write speed capable by the card with faster speeds helping the camera to perform at its best.

The number of images you can store in a memory card is based on the capacity of memory on the card, the resolution of your camera, and the quality selection you choose for the images and how the camera compresses the images. Before you settle on a specific size of memory card, be sure to get specific estimates from your camera manufacturer or reseller regarding how many pictures you can fit on a given-size card at each resolution.

Click here for a capacity chart of memory card size compared to camera megapixel.

Lexar makes memory cards in capacities of 32-megabytes to 8-Gigabytes. A 32-megabyte card in a 5-megapixel camera in high-resolution JPEG mode will store only about 12 images. While a 8-Gigabyte card will store more than 3000 images. When choosing a memory card, buy what you think you'll need for a maximum day's shooting. And remember, more memory means more pictures so buy more than you think you need. In the end, you'll be happy you did.

Most digital cameras include a starter memory card. Starter cards are usually low capacity memory cards that allow you to get started with your new camera right away, but ultimately become a source of frustration because of the limited number of images the camera is able to store. When you upgrade to a larger memory card, you can take more photos before you have to make decisions about which images to keep and which to delete. Most pro's use more than one memory card, filling one, inserting another, and continuing to shoot pictures just as they used to change the film. Pros will typically use 6 - 12 memory cards. Even if you're not that serious about photography, your best experience will be with 2 or 3 memory cards.

Some of the rationale for having more memory cards goes back to the fundamental difference between shooting digital versus film. With digital you no longer need to buy film. You can shoot pictures and never worry about the cost of film and developing, or even what the pictures look like, until you have a chance to cull them on your computer. You can even give the camera to a youngster to develop his or her photographic skills at virtually no cost. And you have the nearly instantaneous gratification of seeing the output increase the excitement. Don't let a simple thing like memory come between you and a photography experience of wanton abandon.