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REVIEW: Lexar Professional 3400x CFast 2.0 Card

Lexar’s CFast 2.0 card system works great on the new Canon C300 Mk II

With the delivery of my new Canon C300 Mk II, I’ve had to retire my trusty CF card collection, which served my original C300 so well for nearly 4 years. But the C300 Mk II, with its 4K and raw recording modes, requires CFast 2.0 cards, which look like CF cards but are much faster and, of course, more expensive.

lexar main

When I went looking for CFast cards, I could choose from a number of vendors, including SanDisk, Lexar, Transcend and others. But I chose Lexar’s Professional 256GB card ($629 at B&H) and it’s been working flawlessly with the Mk II. Here are some specifics on why I chose Lexar, and how its card performs…

  • The card is indeed fast, with an advertised read speed of 510 MB/s and a write of 450 MB/s. That write speed is fast enough to keep up with the Mk II’s 4K maximum data rate of 410MB/s, and its read speed makes it very fast for offloading data (more on that below). I’ve shot with the card at multiple 4K/2K/1080 frame rates, with the card empty and near capacity, and it performed perfectly.
  • The Lexar grabbed my eye because it’s one of the few CFast cards available in a whopping 256GB capacity. Shooting 4K/24fps with the card gives you 85 minutes of capacity, which still makes the card useful for long-form shooting like interviews or documentary work. In comparison, SanDisk’s biggest card is 128GB, which reminded me of the olden days when I was shooting with 32GB P2 cards on my HPX2700, and copying cards multiple times during a shoot. I didn’t want to go back to those primitive times, so the Lexar card was appealing. As for Transcend, it did have a 256GB card as well, but its top write speed of 370 MB/s meant that it couldn’t handle the Mk II’s richest data rates.
  • I also chose the Lexar card after calling Canon tech support, and learning that they have successfully tested both the Lexar and Sandisk cards, but no others yet.
  • Cost-wise, Lexar’s card is reasonable by the standards of CFast cards, especially given its higher capacity. In comparison, SanDisk’s 128GB is $369, so buying two of those would be significantly more expensive than Lexar’s single card. And Transcend’s 256GB card is $599 but, again, its 370MB/s write speed is lower than what the C300 MkII requires.


lexar card reader

I didn’t find the Thunderbolt card reader was apprecibly faster than the USB 3 reader, but it gives you more flexibility when you’ve got limited ports on a laptop. 


Lexar Card Readers

Lexar sells a couple of good CFast card readers, including the Lexar CR1 (USB 3, $19.99 at B&H) and the CR2 (USB 3 and Thunderbolt 2, $88 at B&H). Both card readers are fast using USB 3, provided you’re copying your footage to a fast drive. For instance, I used the CR2’s USB 3 port to copy the full card to an 8-drive, Thunderbolt-2 RAID, taking 26 minutes, 51 seconds. I used Shotput Pro to do the copy, which adds a little time for Shotput to do its bit-for-bit safety verification. Next, I tried copying the same card to a single SSD connected to my Mac Pro via USB 3, and that copy took 29:31. I also tried the copies using the CR2’s Thunderbolt 2 interface, but only shaved a minute off of each copy time. Saving a minute doesn’t justify the higher price of the CR2 vs the USB 3-only CR1, but I do like having the option to copy cards from Thunderbolt, leaving limited USB 3 ports on a laptop free for multiple drives. Anyway, all of these copy times are pretty impressive for a 256Gb card, but just keep in mind that a fast card or reader can’t help you if you’re offloading to a spinning hard drive. Case in point: when I tried to copy the same 256GB card to a 5400 RPM portable field drive, the copy took almost an hour and 20 minutes.

One last thing regarding Lexar’s card readers: they work as stand-alone readers, but they’re also designed to plug into a small, 4-bay hub also made by Lexar (the HR1 is USB 3, and the HR2 adds Thunderbolt 2). If you’re doing a lot of media management, being able to plug these into a vertical hub saves desk space and cable clutter, and the hub also accepts other Lexar readers that can handle CF, SD and other card formats.



lexar hub

Lexar’s HR1 and HR2 also accept solid state storage modules for copying footage from cards. 


Two New CFast Cards from Lexar

Right before press time, Lexar began to ship a new 3500x card that’s replacing the one I worked with. It’s got the same write speed of the 3400x card you’ve just read about, but a slightly faster read speed of 525 MB/s versus the 3400x card’s 510 MB/s. Lexar is also shipping a new 3600x card that’s specifically designed to work with Arri cameras like the Amira or Alexa Mini. Its write speed is no different than the 3500x card, but has a higher read speed (540 MB/s) and Lexar says its firmware is especially tweaked for the Alexa. You can see a breakdown of all three card types here


Summing It Up

Right now, Lexar has the best option I’ve found for new C300 Mk owners. The 3400x card I tested is a fast, reliable card, and it’s combined with the only 256GB capacity currently shipping that can keep up with the Mk II’s data rates.



  • Fast, reliable card worked perfectly with the C300 Mk II on a variety of projects
  • Only card Ive found with a 256GB capacity that also satisfies Mk II data rates
  • Lexar makes affordable, fast card readers as well
  • Good offload speeds when saving to an SSD in the field (under 30 minutes for 256GB)
  • Middle of the road price compared to the competition



  • Looding forward to lower prices as CFast cards become more common!


Helmut Kobler is a Los Angeeles-based DP and cameraman at: www.losangelescameraman.com




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Helmut Kobler is a DP and cameraman based in Los Angeles, California. He’s shot for networks such as Discovery, The History Channel, the BBC, PBS and others. Corporate work includes projects for Microsoft, American Express,…

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