Using the CFExpress memory card
If you want to use the full speed of these fast memory cards, you'll need fast USB connections on your computer or laptop. Anything below USB 3.1 Gen2 with a transfer speed of up to 10 gigabits per second will slow down today's readers, so the speed drops considerably on a slower USB connection (3.1 Gen1 with a maximum of 5 gigabits per second). The data flows at up to 410 megabytes per second — still faster than all other current cards, but at the same time less than half the speed of 3.1 Gen2. Unfortunately, the Sandisk reader doesn't support Thunderbolt 3 or USB 3.2 — those connections, at 20 gigabits per second, would be fast enough to run the memory cards at high speed.
CFExpress cards are true high-speed memory cards that meet all the demands of the latest, most modern cameras for high-resolution photos and films.
CFExpress memory cards are fast by design. The maximum performance of a CFExpress memory card of type C, currently the fastest of the three speed classes, is 4,000 MB/s.
A good UHS-II SD card achieves more than 300 MB/s, i.e. 1/7 of the CFExpress card of type B. The XQD card is a factor of 3 slower than the CFExpress card. This makes the speed of the CFExpress memory card comparable to the SSD hard drives in a computer. Not everyone needs them, but once you have them you won't want to be without them.
The differences between the individual CF Express types
If you take a good look at the three different types of CF Express cards, you'll notice that they are physically different. The CFExpress Type A is the smallest card and measures 20 millimetres wide, 28 millimetres long and 2.8 millimetres thick, including the area for the label.
Type B cards measure 38.5 x 29.6 x 3.8 millimetres, while Type C memory cards measure 54 x 74 x 4.8 millimetres.
Videographers and photographers don't need to worry too much about Type C, as these larger cards are mainly intended for use with computers and solid state drives. Type B is generally compatible with all cameras — this type can be used with a Nikon Z6, Canon EOS R5, Panasonic S1R and mirrorless cameras from other manufacturers. One of the reasons for this is that Type B cards are physically the same size and the same as XQD memory cards.
So if a camera has an XQD slot, usually only a firmware update is needed to become CFExpress-compatible. If you look at the CFExpress card more closely, you may come across the addition Type B. Current CFExpress memory cards carry this suffix because the standard also recognises Type A and C cards. Type A is slightly larger than the microSD card and at the same time slower than Type B, because only one PCIe lane is used. With up to 1 gigabyte per second, however, the mini card is still faster than the other current cards. Type C is roughly twice the size of Type B and has four lanes for data. This means data transfers of up to 4 gigabytes per second are possible. At Photospecialist you'll find CFExpress cards and many other memory cards for your camera.
