Digital cameras have been using a memory card system for storing photos for quite some time now. The cameras store photos as jpg files (or in another format, depending on the camera), and all that has to be done is to transfer the card’s contents to your computer’s hard disk to be able to see a photo, edit it or print it out. At the time when digital cameras came onto the market, the only way to connect them to a computer was through a serial port, an extremely slow process. Currently, digital cameras can be connected to the computer’s USB port, providing a faster file transfer rate.

There are several formats of memory card on the market, seeing that the major digital camera makers, instead of following a single joint standard, opted for setting up individual standards. The most outstanding ones are Compact Flash (CF), Memory Stick (MS), MultiMediaCard (MMC), Secure Digital (SD), SmartMedia (SM) and xD.

In this tutorial we will explain in details the technical differences of each one of the leading memory cards standards, since they are not compatible among them. It is important to note that the difference is not on the physical side. An important aspect of cards is their transfer rate or speed. With a faster transfer rate you can not only the files faster to your computer but also when shooting pictures the camera can be ready faster for you to take your next snapshot. Since each camera model uses one type of card, the type of memory card the camera uses can be a very important aspect when buying your digital camera. Power consumption can play a relevant role on battery life and is an aspect one should pay also attention.

Capacity is also one of the most important features of a memory card. Keep in mind that with older standards like MultiMediaCard and SmartMedia you won’t be able to use high-capacity cards (above 256 MB) because they simply don’t exist for these standards. We will be discussing that on our tutorial as well.

Before going ahead, you may want to take a look at the following table. This is a table to help you to choose the memory card size for your camera, based on its resolution, in megapixels. “File size” means the average file size using camera’s “high-resolution” JPEG mode. The actual number of images per card will vary and depends on the camera model and complexity of the scene being photographed. The number on each row indicated the number of pictures a given memory card can hold at a given resolution. For exemple, a 128 MB memory card can hold approximately 106 pictures using 3 megapixel resolution.

Approximate Number of Images per Capacity

Camera Type: File Size 32 MB 64 MB 128 MB 256 MB 512 MB 1 GB 2 GB 4 GB
2 Megapixel
900KB 35 71 142 284 568 1,137 2,275 4,551
3 Megapixel Camera: 1.2MB 26 53 106 213 426 853 1,706 3,413
4 Megapixel Camera: 2MB 16 32 64 128 256 512 1,024 2,048
5 Megapixel Camera: 2.5MB 12 25 51 102 204 409 819 1,638
6 Megapixel Camera: 3.2MB 10 20 40 80 160 320 640 1,280

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.