Posted by: "oryoki2000"
> Flash cards that cost more than these amounts usually are rated for
> higher data transfer speeds. A standard flash card speed is rated
> around 40X, where X = 150,000 bits per second. Faster cards carry
> ratings of 80X to 133X.
Sandisk just came out with the Extreme 4 level cards, a lot faster than
the speeds above. For me it means the Extreme III cards are now cheaper.
> The higher rates of data reading and writing are not necessary for
> audio recording under most circumstances. A 40X card is capable of
> writing data at a rate of (40 x 150,000) = 6 million bits per second.
> If you're recording stereo with a quantization rate of 24/96, the
> data stream is 4.6 million bits per second. That's within the range
> that the 40X card is designed to handle.
>
> So there's no need to purchase the fast flash cards, often labeled
> "Ultra," "Extreme," or "Pro," for audio recording. (You may wish to
> use the faster flash cards for digital photography, where the higher
> card speed decreases the time you must wait between exposures.)
I agree there is no reason as far as current 2 channel recording the
audio in the field. Where there starts to be a reason for faster cards
is in copying all that audio into your computer. Then the faster cards
make a big difference. I use the Extreme III level cards in my digital
photography, which is faster than the camera, and probably even faster
than the next generation camera I might buy. Or at least as I do
photography. But it's a big help as from there I copy to a battery
operated hard disk storage and viewer (a Epson P2000). How much I can
copy per battery charge in the field is determined by copy speed and my
current level of cards are much faster than the next level down and
extremely faster than standard cards. I can copy far more without
recharging.
Right now, a Sony A100 can shoot at it's highest quality jpeg setting
continuously into compact flash cards that are reasonably fast for the
entire capacity of the card. They, however, left off the higher quality
jpeg setting that is on the previous Minolta 5D as the lower speed cards
or their internal processing could not have kept up. People's tendency
to buy cheaper, slower cards, resulted in a compromise in the camera,
they were unwilling to insist on the fastest cards or build for them.
It's also worth noting that if you do both photography and sound you may
be using the cards in both areas. Or may find in the future that you
have more demanding uses even in audio (think surround sound). If you
bought cheap cards you may end up buying it all over as you move up.
Worth thinking ahead.
Walt
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