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Old October 16th 09, 02:18 AM posted to alt.comp.hardware,rec.photo.digital
kony
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Posts: 14
Default Fast and slow SD Cards

On Thu, 15 Oct 2009 16:18:05 GMT,
wrote:

With respect Bob, virtually all SDHC card maufacturers do advertise the
card's speed - on the card itself. You'll see a number (usually within a
circle) which indicates that card's speed and is called "Class".
Respectively,

Class 2 is rated at 2.0 MBytes per second.
Class 4 is rated at 4.0 or 4.8 MBytes per second.
Class 6 is rated at 6.0 MBytes per second.
Class 10 is rated at 10.0 MBytes per second.
Class 15 is rated at 15.0 MBytes per second.
Class 20 rated at 20.0 MBytes per second.
Class 22 is rated at 22.5 MBytes per second.
Class 30 is rated at 30.0 MBytes per second.
Class 40 is rated at 40.0 MBytes per second.
Class 45 is rated at 45.0 MBytes per second.

Regards...



Bob was referring to fast SD, rather than SDHC. To clarify
SD is not class rated it is (nnn)X rated, but many
manufacturers were buying surplus low performance chips and
didn't want to be obligated to provide any particular
minimum performance level so they didn't specify the speed.

However now that flash is so inexpensive per GB, I would not
recommend buying any SD card that isn't at least rated, for
100X or higher rate.