SD card classes, what are '4' '6' and 10 etc.

clangnuts

I'm not sure the class does equate to speed. I have a class 10 card that reads/writes at 95Mbs.

Lifeforms

No, it does equate to speed. Some cards are class 10, write faster, but it still refers to speed.
What card do you have?

patman99

The branded cards tend to be better-made as well. This is important with SD cards as they are very easy to snap in half.

If you buy cheap cards from the net, you can always check them out with 'HW2test'. This checks capacity and write/read speed.
As for cards running faster than the class, this could be down to several factors such as the cards being from a batch that has failed testing at the designed speed so have been retested at lower and lower speeds until all the test units pass. At which point they mark the cards at the new class.

A.Penny.Saved

Sometimes the cards speed is quoted as (###x) such as 633x or 233x etc. This is because Class 10 speed ratings are so low that they don't adequately indicate newer cards speeds which can go well above 10MB/s. Stating a card as Class 10 doesn't do the card justice if it has a 93MB/s speed.

At other times the actual transfer speed is quoted but note that these are frequently decimal rather than binary. 1000 bytes rather than 1024 bytes.

###x is a multiple of CD x1 transfer speed. x1 being 150KiB/s. CD transfer speeds are 2^ numbers (binary), whereas transfer speeds are usually now decimal.

mr_fishbulb

Rochdale_Guy wrote: »

Don't forget some newer SD cards are labelled SD-HC, and won't work in older digital camera's.

Or some card readers.

I recently got a new camera so got some 8GB Sandisk Extreme HD Video cards which aren't recognised by the SD slots on my monitor (my other 2GB ones are fine as they are not SDHC).