Every digital camera has a specific memory storage media requirement. Mostly, these are called "memory cards". There are several types in use today, various memory capacity and speed; Secure Digital (SD), Mini SD, Secure Digital High Capacity (SDHC), Compact Flash (CF-I), MultiMedia Card (MMC), Memory Stick (MS), Smart Media, xD Picture Card (xD), etc.

Only the specified memory card type can be used with any given device. While some types come with "adapters" that allow their use with other card type receptables, this will often NOT work with digital cameras.

The capacity of the memory card is an important factor. All memory devices have a finite limit on the data that can be stored, expressed in computer data Bytes; usually in the millions (MegaByte MB) and hundreds of millions (GigaByte GB).



Digital photograph image files can be quite large, especially in high end DSLR cameras that offer un-compressed images. This provides the highest possible quality of image, but at the cost of using up a lot more memory space. The largest capacity memory card supported by the digital camera is always recommended, however, higher capacity memory cards have a higher cost. A practicable balance between capacity and cost should be reached.

Some memory card manufacturers "cheat" on the memory capacity, by providing storage values "with compression". Since almost all image files are either compressed (such as JPG files), or uncompressed for quality (native of TIFF files); compressed size is almost never possible for digital photographs. The "raw" memory capacity rating should be looked at.

The speed of the memory card is another absolutely essential thing to look at. DSLR cameras are very fast, especially with bracketing and continuous frame shooting (4 or higher frames per second). If a memory card is too slow, the camera has to pause between frames to allow the data to be written out to the memory card. This is undesirable for obvious reasons.


Some memory card manufacturers also cheat in their memory card speed ratings. They may use a multipler value 2X or 4X which sounds as though it is twice or four times faster, but it is simply that many times faster than a CD ROM (which is a useless comparison). The WRITE speed is the important factor, some manufacturers may state a higher READ speed which is useless in the case of digital photography.

Generally, write speed ratings are in MegaBytes per Second MB/s. In the case of SD and SDHC cards, for example, an alternate notation is the "Class" rating. Class 2 means 2 MB/s, Class 4 means 4 MB/s, Class 10 means 10 MB/s, etc.

The memory media requirements supported by the specific digital camera should be scrutinized for this information, and a suitable memory card from a reputable manufacturer (for example, one that offers a warrantee longer than the time it takes to read this page) that has the maximum supported speed, and as high a memory capacity as is financially possible should be chosen.


All memory cards are fragile, both physically and emotionally (well, technologically). Care must be taken in handling, especially during insertion and removal from camera or computer. All memory cards can only "fit" one way, trying to jam it into the socket backwards will damage both ends of the transaction.

The technology is, essentially, a sliver of silicon that is only a few microns thick. All memory cards eventually fail, extreme temperature or physical abuse can accelerate their demise. A good warrantee from a good manufacturer brand will provide some peace of mind about quality of materials used, and replacement. Having multiple cards on hand is also a necessity for every digital photographer, professional or amateur.

The biggest killer of digital camera memory cards, however, is the "Delete" button on the camera. Memory storage technology places data on the memory media as computer files. One flaw that memory media inherited from its ancestors in PC memory is fragmentation. When a file is written out, the data is dumped in a stream of 1s and 0s. Subsequent photo files dump more 1s and 0s. If you delete a file, a "hole" appears in the file directory (think of tearing a page out from the middle of a book). The next image will be written to that (or this, whichever) newly empty space, however, it will not fit exactly into the available space. Part of it will be written elsewhere, which creates another gap in the file directory. The next image again will cause the file to be placed in chunks or fragments. At some point the directory is scrambled beyond repair, the camera will be unable to recognize it and the card will be dead and unusable (and all image files on it will be lost).

NEVER delete an image from the memory card. Leave it in place, after you have downloaded all the image files to a computer, place the memory card back into the digital camera and FORMAT it using the camera's format card feature. This will wipe the file directory clean and place it in a native format that the camera can use and reuse.

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