Digital Photography Now -  
home :: Features :: Accessories
12th November 2009
Lexar Pro UDMA 600X Compact Flash card review
by Ian Burley

Lexar's 600x card is faster, but maybe not by as much as you might expect

600x-rated Lexar Pro compact flash cards are now available and we've been testing a 16GB example. Although some of the latest high-performance cameras, like the new Canon EOS-1D Mark IV and Nikon D3s can make good use of the increased transfer rates offered by 600x cards, the primary advantage to users of less exotic cameras is for faster image download times. But even then, you need to have the right kind of card reader, and this is what we have been saying all along since the introduction of 266x and 300x UDMA cards a couple of years ago.


It's all to do with bottlenecks. Although USB 2.0 Hi-Speed, which is pretty much universal on cameras and PCs these days, is rated at 480 megabits (Mb) per second transmission rate, or 60 megabytes (MB) per second, in theory, in reality few USB devices get near that speed. Using a good quality USB 2.0 Hi-Speed card reader we've only really seen speeds as high as 20MB/sec, a third of the theoretical speed available. Part of the problem is that USB ports on PCs are connected to the computer's internal data bus via relatively old specification pathways. On top of this there are signalling overheads that erode the actual performance of USB 2.0 connected devices.

In theory, a 300X compact flash card should be able to read or write data at up to 300 times 150K bytes per second, or about 44MB per second. There is too much inefficiency in USB to be able to meet this speed, and it's made slightly worse if you connect your card reader to a USB hub.

USB versus FireWire

So what is faster than USB? FireWire, or IEEE 1394, is rated at 400Mb/sec (it's also known as FireWire 400). On paper that's slightly slower than USB Hi-Speed 2.0, but it's a more efficient protocol and so FireWire card readers have the edge over USB ones. But even these are not fast or efficient enough to make full use of the full speed available from 300x cards. Enter stage left: FireWire 800, or IEEE 1394b. But even here we have to be cautious. FireWire 800 is actually limited from its full performance if it is connected to the usual internal PCI bus that many computers are still based on. You can buy FireWire 800 cards for your PC that connect via a standard PCI expansion slot, but you won't get full FireWire 800 performance this way. To enable FireWire 800 to fully stretch its legs, you need a computer that supports PCI Express, the updated PCI bus standard that most new computers now feature.

The PCI Express advantage

If you intend to use a FireWire 800 card reader on your desktop PC, there may be a compatible port already. If not, get a PCI Express FireWire expansion card. If you have a fairly new laptop, look for an Express Card slot. This is the successor to the old PC Card slot that has been the mainstay in laptops for over a decade. Lexar has announced an Express Card 34 UDMA card reader (the 34 refers to the width of the slot in millimetres, there is also a less common 54 type slot) and this actually out-performs UDMA readers even when connected to a FireWire 800 port. We've been promised one of these Express Card readers to test and we'll update this article once that happens.

Write to card Read from card Time to empty a full 16GB card (14.8GB formatted)
seconds MB/sec seconds MB/sec seconds minutes
Lexar Pro UDMA FireWire 800 card reader
Lexar Pro 600x 2.33 GB camera files 86 27.7 52 45.9 330.3 5.5
1.41 GB movie file 46 31.4 24 60.2 251.9 4.2
Lexar Pro 300x 2.33 GB camera files 96 24.9 65 36.7 412.9 6.9
1.41 GB movie file 52 27.8 37 39.0 388.4 6.5
Lexar Pro USB 2.0 card reader
Lexar Pro 600x 2.33 GB camera files 149 16.0 141 16.9 895.6 14.9
1.41 GB movie file 85 17.0 81 17.8 850.2 14.2
Lexar Pro 300x 2.33 GB camera files 151 15.8 140 17.0 889.3 14.8
1.41 GB movie file 87 16.6 81 17.8 850.2 14.2

In the mean time, the table above details the results of testing a new 600x 16GB Lexar Pro CF card, and comparing it to a 300x card. We used a Lexar Pro UDMA FireWire 800 card reader connected to a Belkin PCI Express FireWire port on a typical, if not cutting edge, Windows XP SP3 PC running an AMD Athlon 64 X2 5600+ (2.8GHz) processor and 4GB RAM. We also used a Lexar Pro USB 2.0 Hi-Speed card reader connected to a Belkin four port powered hub. Test files were copied too and from a SATA II hard drive. Incidentally, we tested copying a folder of RAW and JPEG camera files as well as a single 1.4GB movie file. A faster data rate is achieved with the sole movie file because there is less signalling overhead to erode the transfer rate

As you can see, the results delivered via USB 2.0 are much less impressive than via FireWire 800. Performance is practically identical for both the 300X and 600X cards using the USB card reader, indicating that both are limited by the USB bottleneck.

All the FireWire 800 reader tests are significantly faster than with USB. The 300x card read results are more than twice as fast via FireWire 800, and well on the way to being twice as fast when writing to the card. But the 600x card, although faster than the 300x card via FireWire 800, especially in read times, doesn't show such an impressive increase in speed over the 300x card when it comes to write times.

This chart (based on tests copying a folder of camera image files) demonstrates what a difference a UDMA FireWire card reader can make compared to USB, but it also shows that the boost delivered by Lexar's 600x card over 300x is still limited.

In-camera performance

Unfortunately we didn't have any very high performance DSLRs to test the Lexar Pro 600x card with .I do have an Olympus E-3, which is UDMA compatible shoots at a continuous rate of 5 frames per second and the 600x card did deliver some modest improvements. Recording large JPEGs and RAW files simultaneously (two files saver per shot) it squeezed out one extra shot in a continuous burst before the buffer stalled (17 shots compared to 16 with the 300x card). In five seconds of continuous shooting two more shots were recorded with the 600x card. The buffer emptying time with the 600x card was 6 seconds compared to 7.5 seconds with the 300x card. These are small but nevertheless welcome improvements.


Don't think that a 600x card will be twice as fast as a 300x card. Even if you have a 300x card, make sure that your card reader can serve it properly. If your camera is UDMA compatible, you will probably see some small improvements in performance. Users of high-speed professional DSLRs may well see a bigger benefit. Read times off the 600x card, assuming you have an appropriate card reader, are usefully faster than a 300x card. There will be less time twiddling your thumbs when emptying large cards. I'm looking forward to seeing how the Lexar Express Card 34 compares. The bottom line is, a 300x 16GB card at around 85 is still better value than a 600X one for not much change from 200, but a 600x card is an investment that you may feel is worth paying a premium for now. Will prices drop? The answer is, probably, but there is no guarantee!

Last but not least, included in the price is a licence to download Lexar's Image Rescue 4 file recovery software.


Reader feedback:

Discuss this story:

Lexar Pro UDMA 600X Compact Flash card review

DPNow Lexar Pro UDMA 600X Compact Flash card review
Here is a summary or excerpt from an article that has just been published on DPNow: Compared to Lex... (more)

Stephen Re: Lexar Pro UDMA 600X Compact Flash card review
You mentioned Express cards as an alternative to card readers on laptops. I have one in my Macbook... (more)

Ian Re: Lexar Pro UDMA 600X Compact Flash card review
Basic Express Cards are actually connected to the USB sub-system in your laptop. There are full-sp... (more)

Ian Re: Lexar Pro UDMA 600X Compact Flash card review
Lexar have now provided me with an ExpressCard 34 Compact Flash card reader. I will be testing it sh... (more)

©2001-2015 Digital Photography Now, All Rights Reserved.