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We are lucky enough to have both the Lexar 40x 4 GB and Pretec 6 GB Compact Flash cards on hand and have performed a variety of tests on these very high capacity cards. While the Lexar 40x 4 GB is impressive the Pretec 6 GB is even more so considering that it is similar in design to IBM's Microdrive (both a miniature hard disks) but has trumped Hitachi-IBM's new 4 GB Microdrive both in capacity and time to market. The Lexar is likely only to appeal to professionals who require total reliability and performance, the Pretec may well find its way into all sorts of devices, not just digital cameras. We have compared these two cards with SanDisk's new Ultra II 1 GB card and the industry benchmark IBM Microdrive 1 GB.
Phil: This is not an update to our 'Digital Film Comparison' which is admittedly a little out of date. We are hoping to do a complete refresh of the Digital Film Comparison database towards the end of this year.
|Pretec 6 GB, Lexar 40x 4 GB, SanDisk Ultra II 1 GB, IBM Microdrive 1 GB|
|Card||Type||Filesystem format||Weight||True capacity (MiB)|
|Pretec 6 GB||CF Type II||FAT32||23 g||5888 MiB|
|Lexar 40x 4 GB||CF Type II||FAT32||13 g||3924 MiB|
|SanDisk Ultra II 1 GB||CF Type I||FAT16 / FAT32||11 g||976 MiB|
|IBM Microdrive 1 GB||CF Type II||FAT16 / FAT32||15 g||1024 MiB|
The FAT16 filesystem is limited to a maximum capacity of 2 GB, thus any card over 2 GB must be formatted to use the FAT32 filesystem. This obviously means that the camera must also support FAT32, most digital SLR's do as well as some consumer cameras (see our list at the end of this article).
The Pretec card certainly feels the most professional and robust, with its all metal body it's noticeably heavier than the rest and Pretec make a lot from the fact that the physical design of this card comes from their experience of producing military spec CF cards.
|Card||Street price *||Cost/MB||Value added|
|Pretec 6 GB||$4,500||$0.75||Robust metal body|
|Lexar 40x 4 GB||$1,300||$0.33||High speed transfer|
|SanDisk Ultra II 1 GB||$300||$0.30||Compatible with more cameras|
|IBM Microdrive 1 GB||$200||$0.20|
As you can see Pretec doesn't offer anything in the way of value for money, for that hefty price tag you could buy 22 GB worth of IBM Microdrive's or 15 GB worth of SanDisk's Ultra II cards. The Lexar 4 GB is much closer to the average cost/MB and for a professional card with the promise of high performance it appears to be quite a good buy (if you need that much capacity in one card).
In the comparisons below the best performance is highlighted in green, the worst in red.
Firewire card reader / writer
This test was carried out in Windows XP using a Unity CF Digital Firewire reader/writer. Performance was measured by using a 128 MB set of JPEG or RAW images and timing how long each process (read or write) took. Card was formatted before the write process and removed and re-inserted before the read process.
|Card||Read (KB/sec)||Write (KB/sec)|
|Pretec 6 GB||4,166||4,167||2,598||2,819|
|Lexar 40x 4 GB||3,956||3,963||2,599||2,682|
|SanDisk Ultra II 1 GB||4,453||4,457||3,709||3,926|
|IBM Microdrive 1 GB||3,498||3,587||3,487||3,688|
Overall the fastest card here is SanDisk's Ultra II, in the case of a card reader the Read speed is obviously the most important, all the cards performed around the 4 MB/sec level except the IBM Microdrive which was closer to 3.5 MB/sec.
Canon EOS 10D
This test was carried out by shooting a standard resolution chart in drive mode until the buffer was full (9 images of either JPEG or RAW format). The timer was started the instant the CF compartment light came on and stopped as soon as it went off. Performance was calculated by dividing the total size of each batch by the time taken.
|Card||JPEG (KB/sec)||RAW (KB/sec)|
|Pretec 6 GB||963||980|
|Lexar 40x 4 GB||896||894|
|SanDisk Ultra II 1 GB||1,335||1,352|
|IBM Microdrive 1 GB||1,087||1,106|
Once more the SanDisk Ultra II outperforms all other cards by a fairly significant margin, this probably is also connected to the fact that the 10D's CF controller is probably optimized for FAT rather than FAT32.
This test was carried out by shooting a standard resolution chart in drive mode until the buffer was full (12 images of either JPEG or RAW format). The timer was started the instant the CF compartment light came on and stopped as soon as it went off. Performance was calculated by dividing the total size of each batch by the time taken.
|Card||JPEG (KB/sec)||RAW (KB/sec)|
|Pretec 6 GB||1,435||2,885|
|Lexar 40x 4 GB||1,465||3,025|
|SanDisk Ultra II 1 GB||1,511||3,332|
|IBM Microdrive 1 GB||1,178||2,018|
Here the SanDisk Ultra II wins again, however it's much closer and both the Lexar and Pretec cards deliver very similar performance. The E-1 clearly isn't optimized for the IBM Microdrive.
If you want out and out performance and value for money the SanDisk Ultra II Type I card seems hard to beat, it provided consistently high performance while offering a good value proposition. If you're a professional looking for a higher capacity card to use in your professional digital SLR then I would recommend Lexar's 40x 4 GB, performance on a pro camera was similar to the SanDisk Ultra II and the cost/MB is only slightly higher.
Pretec's huge 6 GB card is mighty impressive and feels very robust however at the current price it's simply to expensive even for professional photographers.
The last word: I should also say something about putting all your eggs in one basket. While there are definitely advantages to the 4 and 6 GB cards (especially if you shoot RAW) you should also consider what would happen if the card failed, my personal choice would be to carry four or six 1 GB cards and know that I'm reducing the chance of loosing any images.
* Does not confirm compatibility with the Pretec or Lexar cards, please check with your camera manufacturer first