Smart Guide To Memory Cards

One of the fastest growing areas of the camcorder market is models that use removable flash memory cards to store video footage. While camcorders have long included flash memory card slots for saving still photos, it’s only recently that they’ve started using flash memory cards to replace tape, DVD and hard drives as the main storage medium in a camcorder.



Every camcorder manufacturer except Sony uses Secure Digital (SD)and its close cousin Secure Digital High Capacity (SDHC) for their flash memory card-based camcorders. Some flash memory card makers such as Sandisk have begun marketing select SD and SDHC cards as “video” cards. But just because it calls itself a video card doesn’t mean it’s the right one for your camcorder. There are key differences you’ll have to be aware of.

SD/SDHC Card Capacities

SD cards are only available up to 2GB capacities, while SDHC cards are available in 4GB, 8GB, 16GB and 32GB capacities. The higher the capacity, the more video the card can store. If you’re purchasing a standard definition camcorder, you can get away with purchasing an SD card. If you’re considering a high definition camcorder that uses flash memory cards, you will need to purchase an SDHC card.

See this Beginners Guide to HD Camcorders for the difference between standard and high definition camcorders.


While there may be a few hidden exceptions, the overwhelming majority of camcorders on the market accept both SD and SDHC memory cards. If your camcorder says it’s compatible with SDHC cards, it can also accept SD cards. However, if it only accepts SD cards, it cannot accept SDHC cards.

videohd-SDHC-8gbEven if your camcorder accepts SDHC cards, it may not support all cards. Lower cost camcorders may not support higher capacity (16GB, 32GB) SDHC cards. You’ll have to dig around in the fine print to be sure that higher capacities cards are supported.


Speed matters. Especially when you’re capturing live audio and video using your digital camcorder, digital camera or digital audio recorder. As the demands of high definition video and audio increase,flash memory is stepping in as the de-facto solution for those who need high speed memory. High speed SD cards boast fast write times that ensure that no data is lost and that audio and video can be captured with minimal latency.

Choosing reliable, high speed SD cards is an obvious necessity. But the plurality of manufacturers offering SD cards makes it difficult to tell which is the fastest, or at least fast enough. The SD Association addresses this issue by maintaining a number of standards that help consumers choose SD cards based on speed.

Currently, the SD Association recognizes two Speed Classes: “Speed Class” and “UHS Speed Class.” Speed Class applies to SD, miniSD, microSD, SDHC, miniSDHC, microSDHC, SDXC and microSDXC cards. These are denoted by a class number within a C-shaped logo. The higher the class number, the faster the card. In order to bear the SD Speed Class logo, card manufacturers have to adhere to the minimum standards set out by the SD Association.

Class 2 is the slowest SD card speed. Class 2 has a write speed of about 2 Mb/s and is suitable for standard definition video recording. Class 4 and Class 6 have write speeds of about 4 Mb/s and 6 Mb/s, respectively, and can be used for HD video recording. These three classes of SD cards are designed to operate under the normal bus interface.

Class 10 SD cards have write speeds of 10 Mb/s and up and are designed to operate under the high speed bus interface.

Beyond Class 10 is the UHS Speed Class. UHS stands for ultra high speed and includes cards that have speeds up to 312 Mb/s. The UHS speed class logo includes a number contained within a U-shape. Currently, there is only one UHS speed class: UHS Speed Class 1, which is designed for the UHS bus interface. Cards in this class will usually be noted as SDHC UHS-I or SDXC UHS-I.

Note that in order to read/write to a SDHC UHS-I or SDXC UHS-I card, you’ll have to have a device that is capable of using both SDHC/SDXC and UHS-I cards. Note that you can use normal Speed Class cards in a device that supports UHS class cards.

What Speed Do You Need?

To help you find the right speed, SD/SDHC cards are broken down into four classes: Class 2, Class 4, Class 6 and Class 10. Class 2 cards offer a minimum sustained data rate of 2 megabytes per second (MBps), Class 4 of 4MBps and Class 6 of 6MBps and Class 10 of 10MBps. Depending on which manufacturer is selling the card, the speed class will either be prominently displayed or buried in the specs. Either way, look for it.

For standard definition camcorders, an SD/SDHC card with a Class 2 speed is all you would need. It’s fast enough to handle the highest quality standard definition video you can record. For high definition camcorders, you’re safest going with a Class 6 card. While you may be tempted to spring for a Class 10 card, you'll be paying for performance you don't need in a digital camcorder.

SDXC Cards

SDHC cards will be on the market for a while yet, but a successor has already arrived. The SDXC card looks like your average SD/SDHC card, but will eventually boast capacities as high as 2TB and data speeds as high as 300MBps. It will take years to hit those performance specs, of course, but it's fun imagining what type of camcorder would need such a high-powered card. To learn more about SDXC cards, see our buying guide here.


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