Want a new memory card for your digital camera, camcorder or other gadget but you’re not sure which one to buy? We help explain the key differences between cards so that you can choose the best one for you.
Small in size and re-recordable, memory cards use flash memory to store digital files – anything from text, pictures, to audio and video. You’ll find them in digital cameras, camcorders, mobile phones, MP3 players and other portable devices.
Memory cards come in all shapes, sizes and speeds, so picking the right one for each of your gadgets can be tricky. The key things to consider when choosing a card are compatibility, capacity and speed.
First off, you’ll need to know which type of card your portable device supports. Most gadgets use only one type of memory card, although some cameras and camcorders have a dual slot that accepts two card varieties. For example, compact digital cameras generally use SD or SDHC cards, while most digital SLRs will support larger-sized Compact Flash cards. Smartphones and MP3 players typically use very small microSD cards.
Older devices may be unable to work with a newer card, even if it fits into the memory slot. For example, an older digital camera with an SD slot will typically be unable to read the newer SDHC card.
A memory card’s storage capacity is measured in gigabytes (GB). The bigger the capacity of a card, the more you can store on it. How much you need depend on the type of files you want to store. Video and image files will use more capacity than text and music, while the biggest space hogs are HD video footage and photos shot in RAW mode.
Memory cards are classified by their ‘read/write speed’ or ‘data-transfer rate’, which describes how quickly a cards saves and transfers data. A memory card’s speed is given either in megabytes per second (mbps) or using a ‘x’ suffix, such as ‘150x speed’.
A new rating system has been introduced for the SD cards that ranks speeds into classes to make it easier to choose the most suitable card for your device. It ranks cards into four classes showing the card’s minimum transfer speed. So you can be certain that while you may get better transfer speeds when using the card with your device, you won’t get less than the speed detailed.
The class ratings are as follows:
|Class rating||Minimum transfer speed||Equivalent
|2||2MBps||16x||recording standard-definition (SD) video|
|4||4MBps||32x||recording high-definition (HD) video,
|6||6MBps||38x||recording high-definition (HD) video,
taking HD photos
|10||10MBps||100x||recording 1080p HD video,
taking photos in burst shooting mode
What card speed do you need depends on how you use your gadget. Using your digital camera’s burst mode with a fast card will see images capture more quickly so there’s less downtime before you can take another photo. In contrast, there’s less need for a fast card in mobile phones and MP3 players, as they mainly transfer data between devices.
Most manufacturers list compatibility, capacity and speed information on the card’s packaging. Typically listed will be the card’s speed and class rating, the types of data – such as images and SD/HD video – the card supports, and the recording time for video or the maximum number of images that can be stored.
Types of memory cards
SD and SDHC – Secure Digital (SD) cards can be found in everything from cameras to MP3 players. They’re small in size and many have a switch on the side that locks the card to prevent data being overwritten or erased.
For the most part, SD cards have been superseded by the newer format SDHC, which offers higher speeds and capacities from 4GB up to 32GB. The latest format to be introduced is SDXC which supports much larger storage capacities – potentially up to 2TB. However, the availability of SDXC cards is still somewhat limited and the current maximum size of these cards is 256GB.
Backwards compatibility is an issue with this type of card as new formats are released. On older SD-only gadget may be unable to use the newer SDHC and SDXC cards
MicroSD and microSDHC – As small as a fingernail, microSD is the smallest type of memory card available. Found mostly in mobile phones and MP3 players, they can store up to 2GB, although the newer format microSDHC offer larger storage capacities from 4GB-32GB.
Compact Flash – One of the oldest types of flash memory, CompactFlash (CF) cards are larger and more durable than SD cards. Mainly used by high-end digital SLR cameras from the likes of Canon, Nikon and Pentax, they provide fast transfer speed and big storage capacities up to 128GB.
Compact Flash is available in two varieties: type I and type II. The only difference being that type II is slightly thicker in size. Most cameras support both types but check before you buy.
MemoryStick – MemoryStick is Sony’s own Flash memory storage format that’s used on all its digital devices including cameras, camcorders, MP3 players, mobile phones and its PSP games console. However, many Sony cameras now include support for SD/SDHC cards.
Memory Sticks come in range of sizes and specifications, with adaptors to fit them in different-sized slots. The latest version, the Memory Stick Pro-HG Duo is three times faster than the original MemoryStick Pro cards and comes in capacities up to 32GB.