On 3/31/2013 6:48 AM, Bob Whitmire wrote:
> I'm in the market for some fast SD cards, as the D800 files are somewhat
> hefty and the standard issue SD or CF takes a bit of time to write.
It can be a bit confusing. (I'm only up to date on SD, so you are on your own
for CF.)
First, we had all the 'X' speed designations, which obviously were not
standardized, and in some cases seemed to have
been designated by marketing.
Then we had 'class x' ratings, which are much more meaningful, but have peaked
at Class 10.
UHS* is actually a different interface protocol**, and requires that the camera
understand it. Your D800 can do UHS-1.
UHS-2 exists as a spec. Wikipedia says no cards exist as yet and I doubt any
cameras yet support it.
(There's an in between mode, called UHS104, which supports twice the clock
freq. and transfer speed. Sandisk, at least,
has cards with rated write speed of 90MB/s which means they must have this. But
what devices may be able to use it, I
have no idea. Sounds like something to gull us into paying for capability our
cameras can't use.)
But for you, and me, it's UHS-1.
I came to try them when B&H had a closeout sale of Sonys, two 32 GB cards for
$35. They claim a write speed of 45Mbps,
4.5 times the Class 10 spec and near the theoretical 50 max. of the spec.
NOTE: The speeds on the card labels are meaningless for camera use. They are
read speeds***, not write speeds. A card
like the Sandisk Extreme 8GB card sitting in front of me is a Class 10 that
says "30MB/s" on the front. But that's the
read speed; write is 10MB/s.
The Sonys I just got do the same thing, touting 94MB/s on the label. Both
brands have an asterisk on the MB/s label
number, but no footnote on the card.
Ultra Something Moose
* Ultra High Speed, duh.
** Sounds to me like some sort of return from serial to parallel, with a
"four-bit transfer mode" per clock cycle.
*** And indeed, even though not UHS-1, the reader I installed in my computer
does seem faster with the cards with faster
read ratings.
--
What if the Hokey Pokey *IS* what it's all about?
--
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