Memory Cards Explained
While a cheap, supermarket memory card could store as much data as an expensive
card of the same size could, it will be less hardy, probably not waterproof, have slower write and transfer speed, and be less likely to be able to recover lost data. This is why you should go for quality rather than price, unless your budget will not stretch far enough.
Write and Transfer speed
Write speed is how fast data can be moved to the card. This is often expressed in classes. Class 2 has a min speed of 4Megabytes per second, class 4 has a min speed of 8MB/s, but can well also be 15MB/s as demonstrated by SanDisk Ultra ll 4GB memory card. UHS-1 Standard cards are very fast, with about 90MB/s. Memory cards are also divided into classes by their write speed.Class 6 cards are the minimum for HD video. Class 10 cards easily take up HD video and can do 3D too. UHS-Class 1cards are for pro cameras, HD video capture, high quality and 3D.
It goes without saying that a larger card can take more files. Memory card size is measured in megabytes (MB) and Gigabytes (GB) and terabytes (TB). 1MB = 1024 bytes, 1GB = 1024 MB, 1TB = 1024GB. An SLR needs a larger memory card than a compact.
SDHC = High Capacity, but not an outstanding write speed, these cards are suitable for high resolution compact cameras, and the more enthusiastic photographer
Ultra Decent speeds, and decent capacities, suited as above
Ultra ll Suitable for high res compacts, and lower res slrs
Extreme High speed for high res DSLRs
Extreme Pro 3D, HD video, amazing speed of 90MB/s
SDSC = Secure Digital Standard Capacity,
SDXC = Secure Digital Xtra Capacity
SD = Secure Digital or
SD = SanDisk
Eye- Fi = With Wi-Fi for easy transfer
CF = Compact Flash memory cards offer high transfer, and write speeds