Pentax *istD can't exploit fast cards such as Lexar WA cards

I raised this subject in a thread "Pentax *istD & Lexar WA technology -
any experience?". (No responses!) I wondered why my Pentax was only
writing to a Lexar 80x WA card at 2MB per second, although the card
supports 12MB per second even without Write Acceleration technology,
and should be up to 23% faster with WA technology.

I have had a long on-line dialogue with Lexar support, and a
substantial telephone conversation with a Lexar technician. The
conclusion appears to be that the Pentax *istD is incapable of writing
to ANY card much better than 2MB per second, whatever the speed of the
card or the acceleration technology supposedly used.

This suggests that if you want faster write speed than 2MB per second,
don't buy a Pentax *istD. And if you have a Pentax *istD, you may see
no performance advantage from a card that is significantly faster than
2MB per second. The bottleneck appears to be in the Pentax, not in the
card. And that applies to Sandisk Ultra II cards too.

In the Lexar labs, their bus analyser shows that the Pentax does indeed
use the WA standard. But it takes 5.7 seconds to transfer 14MB, even
without the extra overheads that the Pentax needs to store a Raw file.
Lexar's tests of the Pentax writing to a Sandisk Ultra II card was 6
seconds, very little difference. The 7 seconds I was seeing for a 13MB
file included overheads that their bus analyser wasn't looking at. All
these figures are probably reasonably consistent.

Lexar promote the fact that the Pentax *istD supports WA technology.
But the slowest Lexar card with WA technology is far faster than the
Pentax can handle even WITHOUT WA technology! It may be that WA
technology in the Pentax *istD is totally irrelevant, used for mutual
Pentax/Lexar promotion, not for photographer benefit.

--
Barry Pearson
www.barry.pearson.name/photography