Join Date: Jul 2009
Location: Calgary, Alberta, Canada.
Class 6 and class 10 may not mean much. Class 10 is a fairly new category and memory cards were much faster before the category was created. In fact, there are many that are faster than Class 10 and there is no category for them. The SD Association is unfortunately too slow creating these, but the idea is great. What you need to look for is the "x" rating or the actual MB/s number which is sometimes listed in the spec sheet.
Here's what the classes mean:
Class 6 means the card reads and writes at least 6 megabytes per second
Class 10 means the card reads and writes at least 10 megabytes per second
The "x" number gives you the actual speed. Each x = 150 KB/s. So if you have a card that says 150x that means it reads and writes at 22.5 megabytes per second (150 x 150KB/s = 22,500KB/s or 22.5MB/s), which means it could be both Class 6 and Class 10. It really should be in a category of Class 22, but there is no such category, so they either put it as Class 6 on the market, or if they manufactured it after the new class was created, they would have labelled it Class 10.
Most cards should indicate the "x" number or the actual MB/s. Unfortunately SanDisk started this trend where instead of using actual numbers they started naming their cards "ultra", "extreme" "extreme pro" "ultra extreme pro" "crazy ultra super extreme pro fast" to appeal to the dumb-ass consumer. They were successful, everyone thinks they're the best and they pay a hell of a lot more money to have their fancily named cards. Fortunately the SD Association started regulating the speeds with those class numbers, they're just a bit slow to catch up.