SD card read/write speeds

Interesting article on Pages 54-57 of the November (!) 2012 edition of PC Pro magazine (my copy is subscription, but it may not be on the newstands yet).

It compares various SDHC & SDXC cards in what looks like a K-R (although it does not say that in the text, the illustration is of the top of one and it refers to 12 megapixel file sizes - which is what the K-R can do)

It shows continuous write speeds in JPEG & RAW modes for 6 cards, and, ignoring the Class 4 cards, the top three (in ascending order) are: Kingston 16GB Class 10 (SDHC) , Sandisk Extreme 32GB(SDHC) and Kingston 233X 64GB (SDXC). The latter two are much faster and empty the buffer much quicker than even the 16GB Class 10.

Was the sandisk the extreme or extreme pro??? The pro is 95mb/s compared to 45mb/s on the extreme....

According to the photos of all the cards, it was a 32MB 45MB/s (not "45mb/s" - would not use that in a camera ) Sandisk Extreme SDHC Class 10 card with a "1" in a "U" to indicate that it is an "Ultra-High Speed" unit.
By comparison, the Kingston is marked "64GB", "SDXC", "I" "1" in a "U"", "ultimate X233X".
On their figures the Kingston is slightly faster in continuous shooting JPEGs than the Sandisk, but they are pretty even in continuous shooting in RAW mode (with the former maybe a little quicker at the start for less than 1s - after that they appear even).

John

Hmm that's strange results, I have never seen any difference in shooting speed in any card of 20MB/s or more in either the gx20, k-r or the k-5 in my tests. I also don't see how the first second can be any faster as the buffer would not be filled by a second of shooting which on the k-r would be 6 shots.

Looks like the Kingston SDXC card has a write speed up to 35mb/s I think the sandisk has a write speed of 30mb/s but shooting speed is limited by the camera body up to 20mb/s rather than card limitation...

I noticed slight differences between 8GB Cl 10 Transend and 7-day shop cards - IIRC the Transcend started quicker but the 7-Day shop card "caught up and passed it" (thus saving images more quickly overall) on the K-5.

Also I bought some of the Sandisk Extreme 16GB cards recently, and they are faster to clear the buffer than either the Transcend or the 7-Day shop cards when shooting about 8-10 frames continuous at airshows.

Yes that's why I said cards with a write speed of 20mb/s or more the transcends are 17mb/s despite what they say and I wouldn't have thought the 7 day cards would have been faster than 20 mb/s

The later transcend class 10 cards where actually slower than the previous version....

I have tried so many cards over the last year, reading speed is a crucial part of my workflow. I spend more time waiting for images to transfer from card to laptop than I do on editing, so have done much testing over the last year.

The san disk extreme pro cards are the fastest I have used and for the price are excellent.

I have yet to find a card that writes faster than 20 mb/s that files more than 23 shots on the k-5 before the buffer fills and fps slows down, so this must be the maximum speed the k-5 writes at, iirc the gx20 wrote 22 shots before the buffer filled but that shoots at 3 fps.

ditto

www.pentaxuser.co.uk/forum/topic/card-speeds----29905#comm339405

FYI, a lot of the 4-page article is devoted to card reading issues, so it might be worth a browse when the Nov issue of the mag turns up on the newstands (not sure it's worth buying the mag just for that though - I buy it for other reasons)

John

will have alook when I see it in the shelf