Secure Digital memory cards are becoming more popular in all sorts of cameras, and as maximum limits approach terabyte capacities, the format is poised to be the mainstay for still and HD video shooting in the future
To date, Class 10 is the fastest speed available. Transcend has been in the memory business for 20 years and offers a full line of memory modules, USB flash drives and portable hard drives, MP3 players and other multimedia products—including their Ultimate Class 10 SDHC cards, with storage capacity up to 16 GB. In addition, they provide even higher burst rates of up to 16 MB/s write speed, making them ideally suited to shooting full HD 1080p video.
One thousand times more capacity than SD—and a faster data-transfer rate—that’s what SDXC promises. The new standard, announced in April 2009, increases SDHC storage capacity from 32 GB up to 2 TB, and increases bus interface speed up to 104 MB/s as of this writing (with a road map indicating a potential of 300 MB/s in the future). Theoretically, a 2 TB SDXC memory card could store about 480 hours of HD recording. And, the faster bus speeds will allow an increase in the number of frames per second, assuring even greater improvements in overall video quality.
What Exactly Does 133X Mean?
Before the adoption of standardized performance class ratings, card manufacturers used a speed-rating system borrowed from the original CD-ROM. First-generation CD players transferred data at 150 KB/s, the speed that represented the baseline of 1X. A CD player that was 4X could transfer data at 4x150 KB, or 600 KB/s. Play that out to modern SD cards, and you find that a 133X card offers burst speeds of up to 133x150, or 19,960 KB/s. While that sounds confusingly similar to the 20 MB/s promised by a Class 20 card, the hitch is that those speeds are burst speeds, not sustained speeds. It’s not uncommon to find a Class 6 card that’s capable of 20 MB/s for a brief period.
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