----- Averages for "SANDISKIV-8" (1GB/start, 3 iterations) ----- Chunk Size Write MB/sec Read MB/sec 4K 1.2 8.4
8K 6.8 13.3
16K 11.7 19.9 32K 14.7 27.3 64K 25.4 33.3 128K 31.5 37.1 256K 31.4 38.1 512K 31.4 38.9 1MB 31.5 39.3
The results reveal that the maximum claimed speed is not achieved for writes, but that is relatively unimportant, since a card reader is used almost exclusively for reading files. Whether the write speed can be achieved in digital cameras is highly dependent on the camera. Note that large transfer sizes are needed to exploit the speed of the card for either reads or writes. A “dumb” camera will never achieve the claimed speeds.
Faster speed doesn’t translate to improved performance in my Canon EOS 5D, at least not subjectively; it doesn’t feel any faster when taking pictures or playing them back or zooming in.
However, after a $75 rebate, the Extreme IV 8GB card is actually less expensive ($234.95) than its predecessor, the Extreme III ($239.94 after $30 rebate) [B&H prices]. Go figure. Future digital SLRs might well take advantage of the increased speed. Of course, the interaction of new card technologies with existing cameras does not preclude the possibility that the “faster” card could be slower in some cameras, though I’m not aware of any such problem.
The robgalbraith.com Performance Database shows that a 4GB Extreme IV card is a paltry 10% faster than a 4GB Extreme III card in the Canon EOS 5D for RAW writes—an insignificant difference for real work. Nikon D200 results are even less impressive. So the real value is only in improved download speed eg “read” speed, which DiskTester suggests is quite speedy.
On a 2.33 GHz MacBook Pro Core 2 Duo, I copied 6.02GB of image files (1GB = 1024MB) to the Extreme IV and Extreme III cards. I unmounted the card and removed it, then reinserted it and timed how long it took to copy the files back to the hard disk using the Mac OS X Finder (very fast striped RAID hard disk). I used the Extreme reader for both. The speed gains are indeed very real for copying files in a card reader...too bad the gains aren’t applicable to cameras.
|Extreme IV 8GB||Extreme III 8GB|
|Write files||4:05 (25MB/sec)||9:01 (9.76MB/sec)|
|Read files||2:42 (38MB/sec)||7:31 (13.7MB/sec)|
Bottom line: if speed in downloading your shoot is important to your workflow, the Extreme IV is clearly a huge advantage. Perhaps the Extreme III card would perform better in another card reader, but the results above are consistent with previously tested results using a Lexar Firewire card reader.