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GuidesWhat is a CFexpress card, explained

What is a CFexpress card, explained

Nowadays, technology is advancing at breakneck speed. You haven’t even had time to buy yourself a smartphone yet, and a new version of it appears, and you’re not so “cool” anymore.

In general, the same applies to the memory card industry, because there are a huge number of photographers around the world and they need to constantly improve the quality of photos, and with this comes an increase in the capacity of memory cards, as well as data transfer speed.

There are already many variations of memory cards, which vary not only in speed and capacity but also in brands and compatibility, not to mention the price. While SD remains the most common format, there are other formats, including Compact Flash, microSD, XQD, CFexpress, and others that have different advantages and are compatible with different cameras.

As camera technology continues to improve, and 4K video recording is quickly supplanting Full HD video recording (and 8K is just around the corner), storage media must be fast and high-speed to meet the demands of these new technologies.

Increasingly, memory cards require not only a large capacity to store all those images and videos, but also data transfer speeds that allow them to handle all those gigabytes of data. They also have to be able to support the incredibly fast continuous shooting speeds of the latest generation of premium cameras.

So, more about one such memory card, the CFexpress card.

What is CFexpress

CFexpress is a removable storage standard proposed by the CompactFlash Association. The standard allows PCIe bus version 3.0 from 1 to 8 lanes, with a data transfer rate of 1 gigabyte per second on each lane. The NVMe protocol is used to provide low latency and reduce overhead. There are several CFX form factors with different numbers of PCIe lanes per slot.

One of the goals of the standard is to unify the removable media ecosystem and use the widely used PCIe and NVMe standards. There’s a wide range of controllers, drivers, and drives that use these standards.

How to use a CFexpress card in any camera

Actually, you cannot use a CFexpress card in any camera. That’s why many cameras today are designed for SD cards, and CFexpress cards are still in rotation.

The CFexpress card types are also each different in size.

  • The Type A cards are 20x28x2.8 and have a maximum theoretical speed of 1GB/s.
  • The Type B cards are slightly larger, 38.5×29.8×3.8, and can reach speeds of 2GB/s.
  • The Type C is a larger format (54x74x4.8) and has a higher potential speed of 4GB/s, but none of the manufacturers have used it for their devices yet.

These size differences mean that the card slot has to be designed specifically for them, so you can’t use a CFexpress card in an SD card slot. Cameras with CFexpress card slots are usually compatible with SD cards, which is useful if you can’t afford or don’t need the extra power and want to stick with SD.

For example, the Sony A7S iii camera has two memory card slots into which you can install either CFexpress type A cards or SD cards. Some CFexpress type B cards can also work in the XQD slots.

Another important factor when buying a CFexpress memory card is its sustained write speed. A sustained write and data transfer speed is maintained when the card is in constant use for an extended period of time, which means a good average write speed for the card.

Why is CFexpress so valuable

The reason is that the new format offers significantly higher speeds compared to the current generation media – XQD or SD. It also has serious potential for improvement and several form factors for use in different types of equipment. Furthermore, there’s already the second generation of CFexpress themselves, with new sizes and increased speeds.

Type B cards are currently much more common. Type B CFexpress cards use exactly the same form factor and connectors as XQD cards. That’s why many cameras, such as those in the Nikon Z and Panasonic S lines, that were originally compatible with XQD cards have been able to add CFexpress compatibility via a firmware update.

At the same time, XQD already had a number of advantages over more traditional memory card formats, and XQD cards are significantly smaller than competing CFast cards. Therefore, it’s not surprising that CFexpress started its expansion with a form factor similar to XQD.



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