Canon R5 Memory Card Guide: CFexpress Type B & SDXC Specs

The Canon EOS R5 utilizes a mixed dual-slot storage system. Slot 1 takes high-speed CFexpress Type B cards, while Slot 2 takes standard UHS-II SDXC cards.

The R5 Mark II uses the same pairing — one CFexpress Type B slot and one UHS-II SD slot — so cards bought for one body work in the other.

You don’t technically have to fill both slots for the camera to function. If you just want to shoot standard photos or basic 4K video, a single SD card works fine. However, to unlock the R5’s flagship capabilities — specifically 8K RAW video and 4K at 120fps — you must use the CFexpress slot. Here is a practical look at how I manage this dual-format workflow and match memory card speeds to the camera’s actual hardware limits.

Quick recommendations

If you just want to grab the right gear and get out shooting, these are the cards and readers I rely on for the R5. Based on my independent memory card speed tests, they meet the camera’s demanding bandwidth requirements for high-end video and fast burst rates without overpaying for speeds the camera can’t use.

• Slot 1: CFexpress Type B
• Slot 2: SDXC V90 UHS-II
• Dual CFexpress B / SDXC UHS-II Memory Card Reader

Sample Images: You can see some of the photos I’ve taken with the Canon EOS R5 here.

Canon R5 card slots: Compatibility & requirements

Slot 1: CFexpress Type B & the 4.0 opportunity

CFexpress cards come in three distinct physical sizes: Type A, Type B, and Type C. They are not interchangeable. The Canon R5 strictly requires CFexpress Type B.

One point that trips people up: XQD cards are exactly the same physical size as CFexpress Type B, so an old XQD card will slide straight into the R5’s slot. The camera won’t use it. Canon lists only CFexpress Type B as compatible, and no firmware update has changed that, so XQD cards you might have left over from a Nikon body are no help here.

The main appeal of CFexpress Type B is raw speed. While the fastest SD cards peak around 300 MB/s, modern CFexpress Type B cards routinely push sustained write speeds well over 1200 MB/s. You don’t need all of that for 8K RAW, though: the R5’s 8K RAW mode peaks at 2600 Mbps, which is about 325 MB/s sustained. That’s still more than any SD card can hold up, which is why 8K RAW is CFexpress-only. For movie recording Canon’s own guidance is a CFexpress card rated VPG400, or one with equivalent sustained write performance.

Should you buy a CFexpress 4.0 card for the R5?

The CFexpress market is currently transitioning from the older 2.0 spec to the newer, twice-as-fast 4.0 spec. Because the cards look identical, navigating this shift is actually a great opportunity to save some cash if you know what to look for.

The Canon R5 is a CFexpress 2.0 camera. It physically lacks the PCIe Gen 4 hardware required to hit the newer 4.0 speeds. This is a hardware limitation that cannot be changed with a firmware update.

Because the CFexpress standard is backward compatible, you can put a bleeding-edge 4.0 card into the R5, and it will work flawlessly. The camera simply throttles that card down to 2.0 speeds. While you won’t see an in-camera performance bump from a 4.0 card, this backward compatibility opens up some opportunities for smart buying. Because, for now, you can often find perfectly capable 2.0 cards significantly cheaper than the newer 4.0 cards.

But it’s not quite that simple all the time. Because manufacturers are aggressively shifting their production lines to the new standard, newer 4.0 cards are sometimes actually cheaper and more readily available than older 2.0 cards. In a market distortion due to algorithmic pricing based on limited availability of legacy cards, I’ve even seen older 2.0 cards show up at massively inflated prices.

So look at the sustained write speeds for the card and go with whatever is cheaper, regardless of whether it’s 2.0 or 4.0. If you spot a 4.0 card for the same price or cheaper than its 2.0 equivalent, grabbing the newer version is a fantastic win. You keep extra money in your pocket, and as a bonus, you unlock drastically faster desktop offload speeds when you get back to your desk (provided you pair it with a USB 4.0 memory card reader).

Canon originally published a list of tested cards for 8K RAW. That list predates the current generation of CFexpress cards, but the high-performance cards listed below easily exceed the camera’s maximum bottleneck requirements:

Slot 2: SDXC (UHS-II)

The second slot utilizes standard SD, SDHC, or SDXC cards. As a practical matter, you should only be looking at SDXC cards (64GB and larger). Because the R5 shoots 45-megapixel stills and massive video files, anything smaller will fill up far too quickly to be useful.

SD cards are inexpensive but significantly slower than CFexpress. If you only put an SD card in the R5, you will be locked out of the 8K RAW and 4K/120p video modes entirely. For the best performance from this secondary slot, I highly recommend a fast UHS-II SDXC card with a V90 rating to ensure your photo buffer clears as fast as the hardware allows.

Managing the dual-slot workflow

While you don’t have to fill both slots, utilizing them together opens up several professional workflow advantages. You can configure the camera’s record settings to Auto Switch (sequential overflow), Redundant Backup (identical copies to both cards), or Format Splitting (RAW to CFexpress, JPEG to SD).

However, be aware of the Dual-Slot Bottleneck Trap. If you shoot in Backup mode, the camera can only clear its internal buffer as fast as the slowest card. Pairing a fast CFexpress card with a cheap SD card will instantly throttle your 20fps burst speed to the sluggish rate of the SD card.

The golden rule: Formatting

My golden rule for storage media is to always format the memory card directly in the camera you plan to use it in. This ensures the filesystem is optimized perfectly for the R5. You can find the memory card format setting in the R5 menu under the Wrench Icon > Tab #1 > Format Card.

If you accidentally format the wrong card in the field, stop shooting immediately. Because the camera performs a “high-level format” that wipes the directory index but leaves the actual image data untouched, you can usually recover your deleted photos as long as you haven’t written new files over the old data.

If your memory card has started performing sluggishly, I recommend a Low-Level Format. This formats every recordable sector on the card rather than just the directory, which takes a good deal longer than a normal format but acts as a deep reset for the card.

Things worth knowing

• Video File Chaptering: Use 64GB+ cards (exFAT) to ensure your video records as a single, continuous stream. Cards 32GB and smaller (FAT32) will chop your footage into 4GB chunks.
• SD Express Warning: The R5 lacks the internal hardware to utilize the SD Express standard. While they fit, they will default to slower UHS-I speeds, making them a poor investment for this body.