Transfer speed claims of three top-of-the-line CompactFlash cards put to the
With each new product cycle, CompactFlash cards get faster, tougher, and more powerful. It seems like only yesterday a 512MB 16x CF card was state of the art. But as camera processors get faster, file sizes increase, and a 512MB 16x card is, for a certain breed of photographer, the CF equivalent of the Yugo.
For the photographic power users -- professional photojournalists, advertising photographers, and wedding shooters -- bigger is better. And a large card must be fast. For these users, 45x is now considered slow.
With these power users in mind, we decided to put three of the big dogs in this arena to the test, looking at the transfer rates each claimed versus actual performance. The three we tested are the SanDisk Extreme IV, with a claimed speed of 266x (claimed 40MB/sec), the Hoodman Professional RAW 280x (claimed 42MB/sec) and the just-announced Lexar Professional UDMA CF card, with a claimed speed of 300x (45MB/sec).
It's not so much the in-camera write speed that is most crucial. That will be limited by the camera's processor and circuitry, represented by the burst rate for RAW and JPEG-only images, and there's no camera in market that is near even the 133x figure yet. You might notice a slight uptick in write time for a big burst, but what is perhaps most crucial is the transfer speed -- getting those gigabytes of images off the CF card and on to the hard drive as fast as possible. A news photographer could miss a deadline as the progress bar slowly fills up with a big, slow card via a slow connection method with a slow reader. At 1x (150kb/sec), it could take hours to download an 8-gigabyte card.
And don't forget the receiving computer. The processor and configuration of the computer is also a major factor.
Despite the potential speed of the cards, it's possible to hit a transfer speed wall with an older, slower computer.
Let's face it, not everyone has a brand-new, fresh from the factory computer. If your computer doesn't have a FireWire 800 connection, only a FireWire 400, this will keep the transfer speeds in a lower gear than these cards are capable of (FireWire 800/IEEE 1349b transfers at 800 megabits/sec. FireWire 400/IEEE 1349a transfers at half this rate: 400 megabits/second.) If you've only got USB2.0 inputs that will mean the max transfer at the USB2.0 speed limit of 480 megabits/second.
A fast card reader should be able to throughput the data from these big fast cards near top transfer speed of these connections.
But here in the Pop Photo lab, we do have big, fast, machines with FW800 connections, and we're going for speed.
We're racing them to test both read and write times with a gigabyte of digital camera files, from card to desktop and from desktop to card on a Macintosh Power PC G5 Tower with a 2.5Ghz CPU, 2GB memory, 512kb cache, and a 1.25GHz bus.
No programs are running during the testing except for the OS and finder. The files are dragged-and-dropped from the desktop to the card, which has been formatted before the test. The folder is renamed, then dragged and dropped back to the desktop. The folder on the card, and the folder copied to the desktop is then sent to the Trash, which is emptied. This process is repeated three times, and the scores are averaged.