✔ 最佳答案
The higher the class, the faster the card is able to write information off the camera and have it transferred into the card. Generally, class 4 is good enough for most modern DSLRs.
For HD recording or professional DSLRs where you'll be burst shooting at an insane rate, a class 6 or higher is recommended. Another difference is that the higher the class, the faster it'll be to tranfer pictures to your computer from the memory card.
I'm not so sure if upgrading to a class 10 memory card will produce any noticeable difference in speed, but it's worth giving it a try since memory cards are so incredibly cheap nowadays (at least when compared to 10 years ago.)