Flash Memory

Flash Memory is, a generic term for solid-state (no moving parts) memory in electronic devices. Flash memory comes in a variety of formats, and can retain stored information without power. The lack of moving parts in flash memory makes them the logical choice for storing data captured by cameras, as other data storage mediums (such as hard drives, CDs, or DVDs) could become damaged as the camera was moved from place to place.

Some of the most common flash medias are:

The Compact Flash format is rather old but still very common. The cards are large (compared with the newer card formats, such as SD and xD), but the larger size allows them to be produced inexpensively and in higher capacities than other card formats. 2 GB on a CF card is very common these days. 4 GB cards are also available, and capacities reach as high as 16 GB for those with overly-full wallets. CF cards are very robust; they are difficult to bend and do not have exposed contacts that could be soiled, so they may safely be stored in your pocket or suitcase.

The interface of CF is a minimized IDE, so they are compatible with IDE-interfaces in every common computer. There are adapters available so that you can use a CF card as kind of hard drive, but this only makes sense in very special cases. There are very cheap adapters for the PCMCIA port for example, which also is just a kind of a minimized IDE-port. These adapters are purely mechanical, so you can easily use the CF cards in your notebook with PCMCIA port. Alternatively, you can use an USB card reader to connect your Compact Flash card to your computer (this is true for every kind of flash memory).

CF-cards can be very fast. They are available in different speeds (with card price and speed being directly related), and fast cards make sense in good DSLR cameras because the user doesn’t need to wait as long for the pictures to be stored. This allows the user to take a very fast and lengthy series of pictures.

These flash memory cards are much smaller and lighter than CF-cards and this is why you can find them in most of the point-and-shoot cameras today. Because of the smaller size it is harder to put a lot of memory in them. They are available in capacities up to 4 GB, but are more expensive than Compact Flash cards.

SD cards can be very fast compared to other kinds of memory cards. For this reason, combined with their size advantage, it is likely that the SD card will be the the successor of the CF card. But until they are less expensive and available in higher capacities, Compact Flash will remain the dominant memory card used in DSLRs (where a large amount of memory is needed).

The contacts of SD cards are exposed, so you should not put them in your suitcase without using a small case for the card to protect those contacts.

MMCs are visually similar to SD cards and most devices that can read and write SD-cards will be able to read and write MMC. MMCs are much slower and not available in high memory capacities. For these reasons, SD cards have succeeded them in digital cameras. However, MMCs may be used in future cameras, as newer versions of the MMC format address the format’s shortcomings, and the format’s proponents are get MMCs back into market.

Smart Media cards are very old, very slow and very thin. It’s possible to bend them (and to break them) easily. They are generally available with a maximum capacity of 256 MB as of this writing.

Smart Media is seldom found in newer products, and has been replaced by Compact Flash. The two formats are similar in design, but CF cards have the controller chip on the card, rather than inside the camera. CF cards also have faster read/write speeds, and are available in higher capacities.

The xD format is an attempt by Olympus and Fuji to bring their own flash format to the market. The cards are very small - roughly half the size of an SD card. They are usually used in Olympus and Fuji point-and-shoot cameras. xD cards are a bit more expensive than SD-Cards, and are only available with a maximum capacity of 2 GB today. See this Wikipedia entry for a list of full advantages/disadvantages.

The Memory Stick format is a proprietary memory card format developed by Sony. It looks like a longer version of the SD card. Sony started this format for its own equipment but other vendors haven’t supported this format well, so you will likely only use them with a Sony camera. At first, there was only one kind of Memory Stick from Sony, but more kinds have been developed due to the need for higher-capacity cards (the first sticks were able to have approximately 256 MB). Sony created a “Duo” version with a switch to activate a second memory-bank. They have since begun offering a higher-capacity “Pro” version, as well as a “Duo Pro” version. However, not all of these formats are compatible with each other, so buyers should be careful to choose an appropriate purchasing a Memory Stick for their camera.

The term “USB memory stick” is confusing, as the term is usually used to refer to Sony’s Memory Stick cards. The memory stick is from Sony and is a little flash-card. USB-sticks (also called: USB key, thumb drive, memory pen, etc.) are the successor of the floppy disk. You can plug them into your computer and store data on it just like a hard drive, but they are rather large compared to other memory cards, so they are not used by digital cameras.

There are USB adapters available for various memory card formats, such as SD and CF cards. This is a nice way to use an SD card both in your camera and with your computer.

I would recommend CF cards for DSLRs and for point-and-shoot because you can get a lot of memory for little money. SD cards are getting cheaper and so they are a good solution for the point-and-shoot too. The other formats are not so common used and so they are a bit more expensive. Just remember these things when you buy your digital camera.

As a general rule, the faster the card, the more expensive it is. You might get a 40x card for half the price of a pro-level 133x card. For a point-and shoot camera, the speed of the card is largely irrelevant, indeed 40x cards will be perfectly adequate for most DSLRs. Also if your use of a card is slow, for landscapes for example, then again, spending extra cash on the fast card may be pointless. If however, you have the latest DSLR with 10MP and 10fps and you regularily shoot sports, then a slow card card slow the camera down, filling the internal buffer while the camera writes your images out to the flash card.

Cards are not equal either, cheap 133x cards do not always seem to perform as well as brands like Lexar or Sandisk for example. It seems to be that you pay for what you get.

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