What is CFexpress and How Does it Compare?
Whether you are shooting photos or videos, your camera will obviously need some sort of storage media to save your files to. If you are in the market for a new camera, you might be tempted to choose one based on its memory card options.
A relatively new memory card format called CFexpress has appeared on the scene. But what exactly is a CFexpress card? Why might you want to use one when there are so many other formats to choose from? And how does CFexpress compare to other memory card formats, such as SD, XQD, or the similarly-named CompactFlash (often shortened to CF), and CFast cards?
Let’s take a look at CFexpress to get a basic understanding of the format and how it stands up to the alternatives.
What is CFexpress?
The quick and easy answer is that CFexpress is another memory card format, but that’s not entirely accurate. CFexpress is better described as a family of memory cards.
Currently, there are three different types of CFexpress: Type A, Type B, and Type C. There is no concern about putting the wrong type of card into a device because they all have different characteristics and are not interchangeable.
CFexpress Type A is the smallest, and also the slowest, of the CFexpress cards. At 20mm x 28mm x 2.8mm, it’s similar in size to an SD card (more specifically, slightly smaller but thicker). It has a maximum write speed of 1 GB/s* and was first introduced to consumer cameras as part of the Sony a7S III. Currently, Sony is the only company making or using CFexpress Type A cards.
*The maximum write speeds listed here and in the types below are theoretical maximum write speeds. Most of the available cards have lower-printed write speeds and likely even lower actual, sustainable write speeds.
CFexpress Type B has a form factor that is identical to XQD cards. Because of this, Type B CFexpress cards have had the fastest adoption. Camera manufacturers have been able to offer CFexpress Type B compatibility from XQD slots by means of a simple firmware update. At 38.5mm x 29.8mm x 3.8mm, they are larger than SD cards (which also gives them the benefit of being more rugged and durable), but smaller than Compact Flash or CFast cards. CFexpress Type B has a maximum write speed of 2 GB/s.
CFexpress Type C is the largest form factor, coming in at 54mm x 74mm x 4.8mm, similar to CompactFlash card size. They also have the fastest write speeds, maxing out at 4 GB/s. There are currently not any consumer cameras available that have CFexpress Type C card slots. Because of their larger size, the expectation is that Type C will likely only ever be available on the largest cameras that need the absolute fastest speeds to handle huge amounts of data, largely limiting them to big cinema cameras.
How Do CFexpress Cards Compare?
Let’s take a quick look at how popular memory cards stack up.
|Dimensions||Maximum Theoretical Write Speed||Fastest Available Write*||Maximum Theoretical Write Speed||Fastest Available Read*|
|SD (Including SDHC and SDXC)||32mm x 24mm x 2.1mm||312 MB/s (UHS-II)||300 MB/s (UHS-II)||312 MB/s||260 MB/s|
|Compact Flash||43mm x 36mm x 3.3mm||167 MB/s||160 MB/s||167 MB/s||155 MB/s|
|CFAST||43mm x 36mm x 3.3mm||540 MB/s||540 MB/s||525 MB/s||450 MB/s|
|XQD||38.5mm x 30mm x 3.8mm||1 GB/s||440 MB/s||1 GB/s||400 MB/s|
|CFexpress Type A||20mm x 28mm x 2.8mm||1 GB/s||700 MB/s||1 GB/s||800 MB/s|
|CFexpress Type B||38.5mm x 30mm x 3.8mm||2 GB/s||1.5 GB/s||2 GB/s||1.7 GB/s|
|CFexpress Type C||54mm x 74mm x 4.8mm||4 GB/s||N/A**||4 GB/s||N/A|
|*Fastest available cards are subject to change at any given time. Actual performance may be lower depending on device|
|**Currently there are no consumer CFexpress Type C options available for real-world comparisons.|
With all of these different memory card types available, why do we need a new format?
Simply put, newer memory card formats are faster than older ones. For still photography, this will only be beneficial in the most extreme cases — particularly long burst shooting at high frame rates. However, with video becoming a big feature in cameras, particularly video with higher resolution and less compression, the minimum speed needed is far greater than what a stills shooter would need. Even now, 4K raw video is pushing the capabilities of many memory cards. 6K and 8K resolutions are already here and more and more cameras are trying to capture higher and higher frame rates. For these uses, you need the fastest memory card possible just to keep up.
One more thing to keep in mind before we discuss different card formats is that these theoretical max speeds are liable to change. SD has already released a UHS-III standard that increases the theoretical max to almost 1 GB/s (though it’s not available in any products at the time of this writing). XQD has room to improve. Even newer CFexpress variations may double their speed capabilities. The information in the chart above should be accurate for now, but it is likely to change.
CFexpress vs. SD
SD memory cards (along with all of their variants, including SDHC/XC and mini/micro SD) are the most common memory card format available. The huge number of devices that already use SD gives them a massive price advantage over other formats.
To give as close to an apples-to-apples comparison as we can, a 64 GB SanDisk Extreme Pro SDXC with 90 MB/s write and 170 MB/s read speeds can be purchased for less than $20. The 64 GB Sandisk Extreme Pro CFexpress Type B card with 800 MB/s write and 1,500 MB/s read speeds is sitting at $100. The CFexpress is far faster, but you can buy 5 of the SD cards for the same price.
In fairness, CFexpress is relatively new. As it grows in popularity, the price should come down. SD cards are likely to remain a staple. It’s easy to imagine SD being your standard option on entry-level to hobbyist-tier cameras with CFexpress filling in the needs of advanced shooters and any camera with serious video capabilities.
One feature that might increase is card slots that are compatible with SD being newly-compatible with CFexpress Type A – an option already available on the Sony a7S III. If the price and performance of such slots can be optimized, it could offer the best of all options.
CFexpress vs. CompactFlash
CompactFlash cards were the standard for professional-grade cameras for many years. But the reality is that they are on their way out. Other options give better performance in smaller packages, often for lower prices. CF cards will have their place for a while longer, especially since there are older camera bodies that use them and are still popular, but eventually they will phase out.
CFexpress vs. CFast
CFast was the first significant push to replace CompactFlash with a faster, more powerful professional-grade successor. While it had some moderate success, it too is reaching the end of its life.
CFexpress vs. XQD
Looking at CFexpress and XQD cards presents another interesting, and potentially challenging, comparison. They are physically identical (at least on the outside), allowing firmware updates to open up XQD slots to be compatible with CFexpress Type B cards. While CFexpress is much faster, the architecture of an XQD slot means that any CFexpress card used in it will be bottlenecked to XQD speeds.
There’s not as direct of a comparison for cards here as there was with the SandDisk SD card example above. XQD cards are often similar in price or a little more expensive (64 GB options cost around $100-$125).
If you have a camera that supports both XQD and CFexpress, which should you choose? If you already have XQD cards, an external XQD reader, and/or other accessories you’ve purchased to take advantage of XQD cards, there isn’t a reason to switch over to CFexpress. But if you are just getting set up and want to try and future-proof your gear, it’s more likely (though not guaranteed) that CFexpress is going to outlast XQD. There’s no downside to using CFexpress if you’re starting from scratch.
When Should You Use CFexpress?
Most of the time, your choice in memory cards is going to boil down to what your camera has the capability to use. But what if you find yourself in a position where you genuinely have the option to use either card format?
If you really, really need the faster speeds of a CFexpress card, other formats are not going to be a substitute. That said, you can absolutely shoot 4K footage at 60 FPS with an SDXC UHS-II memory card.
Conversely, if you’re shooting a lot of really big files, the read speed of a CFexpress card (1,500 MB/s) compared to a UHS-II SD card (170 MB/s) could save a huge amount of time transferring files to your computer. In a production setting, especially one where the cost of the memory cards is not as much of a concern, the amount of time that these transfers can save you could absolutely be a justifiable reason to choose CFexpress.
As discussed above, if you have a kit filled with XQD cards, it’s going to be harder to justify trading them all in for CFexpress options. Write speeds will be identical (due to the slot in the camera bottlenecking a CFexpress card). Transfer speeds, if you are using a dedicated external CFexpress reader, will again be faster, but the difference is going to be less than with an SD card.
What Is the Best CFexpress Card?
Whenever you choose any memory card, you need to consider the tradeoffs between price, performance, and reliability.
If you need a CFexpress Type A card, you’re in luck. There’s one mainstream option: the Sony Tough CFexpress Type A line. At this time, no other card maker is making Type A cards. If you run across another one, be skeptical and do more research on it. Sony also makes Type B cards in their Tough line, which are solid, reliable options.
For Type B cards, there’s a wider range of options. You need to carefully judge what your needs and budget are. You can likely get enough speed out of all of them, but extreme cases may push you to one over another.
Keep in mind that when it comes to the actual performance (i.e. the speed at which the card reads and writes data) in the real world, the card itself is only part of the equation. Using a CFexpress card in an XQD slot or reader will bottleneck the data, keeping you from fully capitalizing on the card’s speed. Similarly, connecting it to your computer through an older USB port could limit your transfer speeds.
Prograde’s premium Cobalt line is arguably the best CFexpress card that money can buy, and you’ll pay a bit more than other options. Available only in 325 and 650 GB sizes, what sets Cobalt cards apart is they are one of the only cards that list a guaranteed minimum speed (assuming the devices you use don’t slow them down), and those minimums are listed at around 1,300 MB/s. While most other cards will have listed maximum speeds around there, few if any will give you an equivalent actual sustained performance.
Delkin’s POWER line of CFexpress may not always match the performance of the Cobalt cards, but they have held up admirably in tests and they have a relatively attractive price point. You can find cheaper CFexpress cards, but most (or all) will be from brands that are largely unknown with no real reputation to inform any expectation of quality. From a sheer price-to- performance perspective, Delkin Power CFexpress cards are perhaps the best bang for your buck.
SanDisk Extreme Pro
SanDisk has been a huge player in memory cards for many years and has built a reputation for solid, reliable products. The Extreme Pro line is a go-to for many people across different memory card formats. It’s a great mid-range option.
One thing to note is that in tests of CFexpress card performance, the 512 GB card seems to be better optimized than the smaller cards, making it a more attractive option.
Like the SanDisk Extreme Pro, the Lexar Professional line of memory cards has been a strong contender for many years. Similar to SanDisk, they are a reliable, mid-range card.
While the ProGrade Cobalt is the best-in-class card, the pricing is prohibitive for many people. ProGrade’s Gold sacrifices top-tier speeds in exchange for a more accessible price point while keeping ProGrade’s overall quality.
As the needs of shooters become ever more complex, the demands placed on a camera’s memory card only increase. While we have seen a number of memory card formats come and go over the years, CFexpress is poised to become a long-lasting standard, claiming the title of go-to format for demanding, professional shooters.