With SDHC memory cards, what is the difference between Class 4 and Class 6? What does this mean?

I have a panasonic FZ50 which is compatable for a SDHC but would like to know which is the best for quality!

With SDHC memory cards, what is the difference between Class 4 and Class 6? What does this mean?
The SDHC classes were supposedly thought out to prevent consumer confusion, but so far it seems to have achieved exactly the opposite.





The class number simply indicates the card's *minimum* sustained write speed, in megabytes per second. Therefore, a Class 2 card can accept data from the camera at a minimum of 2 Mb/sec., while a Class 4 will be able to take it at a minimum 4 Mb/sec., and Class 6 will have a minimum 6 Mb./sec. writing speed.





The confusion stems from the fact that this is a *minimum* write speed: it says nothing of the maximum write speed (fortunately, some manufacturers tell that as well, for example with the old “X” scale, so that 133x = 20 Mbytes/second), not to mention read speeds (from the card to the camera, or to the PC card reader during photo download, or whatever).








To the point: the “Class” specification has ABSOLUTELY NOTHING to do with quality: you'll get exactly the same quality from a Class 2, Class 4 or Class 6 card. The difference will be in the card's speed to store the photo and be ready for the next one.








I'd suggest carefully reading the card's envelope for further information about its speed, besides the Class thing: if it's anything over 10 Mbytes/second, or about 66x, it's enough for your camera (anything over that would be wasted, since the camera itself has a limit on how fast can it transfer to the card).





A Class 6 will usually (but not necessarily) have a good maximum write speed and minimum/maximum read speeds to go along, but you'll probably only notice the extra speed if you use a fast, USB 2.0 or Firewire card reader to transfer photos to the computer -and only during such transfer, not during camera operation itself.
Reply:Class is same as Gigabytes.