CFexpress 4.0 is a new card specification that doubles the potential read and write speed of CFexpress Type A and Type B cards while maintaining the same physical size and shape cards. Currently, no cameras support CFexpress 4.0, so there aren’t any in-camera benefits, though the cards will work. However, you can buy CFexpress 4.0 card readers like the recently reviewed OWC Atlas 4.0 USB4 reader. If you pair a new CFexpress 4.0 card with such a 4.0 reader, you can immediately take advantage of the blazing-fast download speeds (around 3600MB/s!), which, in my testing, cut some file ingest time in half and better.
Based on the questions I have received, this evolving CFexpress specification has been complex for the average consumer to understand. CFexpress 2.0 and 4.0 cards look identical, except for a tiny number 4 on the label of the newer cards. If you aren’t familiar with all the CFexpress card symbols and numbers explained in my guide, they’re easy to miss. If you don’t see a number 4, you have a CFexpress 2.0 card. Even when you know which card specifications you have, questions remain, and today I’m going to try to answer some common ones.
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CFexpress 4.0 Card Reader Download Speeds
In this article, I want to discuss the download speeds of various card and reader configurations based on tests conducted for my recent reviews.
CFexpress 4.0 Card + CFexpress 4.0 Reader
This is the ideal situation. CFexpress 4.0 card readers all use 40Gb/s USB4 connections, which allows you to access the full speed of a CFexpress 4.0 card when ingesting your photos and videos at the end of the day. This is true for both CFexpress 4.0 Type A and Type B cards.
CFexpress 4.0 Card + CFexpress 2.0 Reader
If you have a brand new CFexpress 4.0 card but use it with an old CFexpress 2.0 card reader, the card’s download speed will be limited to half of its potential. You really should upgrade your card reader to unlock this workflow improvement. This is true for both CFexpress 4.0 Type A and Type B cards.
CFexpress 2.0 Card + CFexpress 4.0 Reader
Let’s say you have an existing collection of CFexpress 2.0 cards, and you can’t afford to upgrade them all to CFexpress 4.0 right now, but you can afford to spend $99 on either the OWC Atlas USB4 reader or the ProGrade Digital Type A USB4 Reader or Type B USB4 Reader. In this scenario, will you see any benefits? To answer this one, we need to divide things into Type A and B users.
Type A Users
If you’re a Sony user using CFexpress 2.0 cards, you’ll have been using a USB 3.2 Type A card reader. I can confidently say this because nobody made any other kind of card reader for CFexpress 2.0 Type A cards. USB 3.2 was capped at 10Gb/s, which is theoretically 1250MB/s. However, for various efficiency reasons I don’t fully understand, it was never possible to reach far beyond a read speed of about 650MB/s with even the fastest CFexpress 2.0 Type A cards on the market.
Here’s where it gets interesting. Some of the very best CFexpress 2.0 Type A cards on the market, such as the ProGrade Cobalt cards or Sony’s CFexpress 2.0 Type A TOUGH G cards, were capable of reaching higher read speeds than this, but nobody could ever take advantage of it due to the speed and efficiency of USB 3.2. Now, with the advent of USB4 card readers, you can!
CFexpress card specifications are backward compatible. A 2.0 card can be used in a 4.0 reader. Since USB4 offers so much speed overhead with its 40Gb/s connection, we can finally unlock the full download potential of all older CFexpress 2.0 Type A cards.
The example above shows tests from my review of the ProGrade Digital Cobalt 2.0 Type A card, universally understood to be one of the fastest 2.0 Type A cards on the market. It was tested in ProGrade’s older USB 3.2 reader and then in its newer 4.0 Type A USB4 reader. As you can see, write speeds improved by 33% and read speeds by 55%! Remember, a card’s read speed is the factor that governs your card download speeds. This is a significant increase with potentially major workflow implications for those shooting large volumes or working on tight deadlines.
I can’t tell you with any certainty what download speed improvements you might get from your old CFexpress 2.0 Type A cards in a new 4.0 USB4 reader. If you have a very cheap CFexpress Type A in the first place, there’s a good chance the improvements will be minimal as its speeds may fall below the threshold of USB 3.2. However, if you forked out good money for a decent CFexpress 2.0 Type A card, say a ProGrade Digital Card, Sony TOUGH G, Delkin Black Type A, or Lexar Diamond, you will see some improvement in card download speed by moving to a CFexpress 4.0 USB card reader, even with those older CFexpress 2.0 Type A cards.
Type B Users
If you have some older CFexpress 2.0 Type B cards and are currently using a USB 3.2 card reader, the same story will be valid for you as it was for Type A users. With USB 3.2 capped at 10Gb/s and CFexpress 2.0 cards capable of speeds well above that, upgrading to a new USB4 card reader will bring significant workflow improvements, even if you don’t (yet) upgrade your CFexpress cards.
The one slight difference for Type B users is that there were a few Thunderbolt 3 CFexpress 2.0 Type B readers on the market from people like OWC and ProGrade Digital. Thunderbolt 3’s 20Gb/s connection speed did provide enough overhead to get the maximum out of CFexpress 2.0 card download speeds. These card readers were expensive, and I don’t think they sold very well. Still, if you have one of these readers, upgrading to a USB4 reader is probably not worth it unless you also plan to upgrade your CFexpress card to newer 4.0 versions. If or when you do upgrade to CFexpress 4.0 cards, you will definitely want to ditch the old Thunderbolt 3 reader and buy a USB4 reader as the new 4.0 cards are capable of speeds well in excess of what your Thunderbolt 3 reader is capable of.
