Which CFexpress and SD Cards Should You Buy for the Nikon D850?

The Nikon D850 is a high-resolution powerhouse. Because it is capable of shooting massive 45.7-megapixel RAW files at up to 7 frames per second (or 9 fps with the battery grip), the camera generates data incredibly fast.

To manage all that data, the D850 features a dual memory card slot system:

• Slot 1: XQD / CFexpress Type B
• Slot 2: SDXC (UHS-II)

Navigating these two different formats — especially considering the major firmware update Nikon issued after the camera was released — can be confusing. If you put the wrong cards in, or configure the slots incorrectly, you will cripple the camera’s ability to clear its buffer. Here is a practical look at exactly what you need to buy.

Quick recommendations

If you just want to grab a reliable card and get out shooting, these are the models I recommend. Based on my independent memory card speed tests, these provide the sustained write speeds necessary to keep the D850’s buffer clearing quickly.

Slot 1: CFexpress Type B picks

Heads up! Make sure to get CFexpress Type B.

CFexpress cards come in three completely different physical sizes (Type A, B, and C) that are not interchangeable. A CFexpress Type A card (commonly used by Sony) is physically smaller and will not fit in your D850. Make sure that “Type B” is printed on the label and product listing.

Slot 2: SDXC (UHS-II V90) picks

Requirements, compatibility, and the CFexpress upgrade

If you look at the physical manual that came in the box with the D850, you will see Slot 1 labeled exclusively as an “XQD” slot. However, you should completely ignore XQD cards today — they’re just too slow compared with CFexpress.

XQD is a legacy format. The cards are expensive, max out at around 400 MB/s, and are largely being phased out of production. The modern standard is CFexpress Type B, which utilizes the exact same physical form factor but is capable of blistering write speeds over 1500 MB/s¹.

By upgrading your camera to “C” firmware version 1.20 or newer, Slot 1 will natively accept CFexpress Type B cards. Not only will this maximize how fast the D850 clears those massive 45-megapixel files from its buffer, but it is a much smarter financial investment. If you ever plan to upgrade to a modern mirrorless flagship like the Nikon Z8, your CFexpress cards will carry right over.

Should you buy a CFexpress 4.0 card for the D850?

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 Nikon D850 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 D850, 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.

In a perfectly logical market, you’d just buy the cheapest 2.0 card you could find. But the market is currently shifting. Because manufacturers are aggressively changing their production lines to the new standard, newer 4.0 cards are sometimes actually cheaper and more readily available than the legacy 2.0 cards they replaced. In a market distortion due to algorithmic pricing based on the limited availability of legacy stock, older 2.0 cards frequently show up at massively inflated prices.

The rule of thumb is to look at the sustained write speeds and go with whatever is cheaper, regardless of whether the label says 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 today, and 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).

Because the D850’s maximum video requirement is standard 4K/30p and its burst rate is 7 to 9 fps, you do not need to overpay for ultra-premium cinema cards.

The dual-slot bottleneck

While you do not have to fill both slots, utilizing dual cards gives you excellent data management flexibility in the field. However, you must be extremely careful about how you configure them in the menu.

A modern CFexpress Type B card in Slot 1 can sustain write speeds over 1400 MB/s. Even the absolute fastest UHS-II V90 SD card in Slot 2 will max out at roughly 300 MB/s. This creates a massive performance gap between the two slots.

If you configure the D850 to shoot in Backup Mode (writing duplicate RAW files to both cards simultaneously), the camera cannot clear its internal buffer until the photo is written to both locations. Because the SD card is physically much slower, the entire camera will instantly bottleneck to the speed of the SD card, completely negating the speed advantage of your CFexpress card.

To avoid this while shooting sports, wildlife, or events, I highly recommend configuring the slots to RAW / JPEG or using Slot 2 strictly as an Overflow drive.

Saving money on the SD slot

If you only shoot photos occasionally, or only use Slot 2 as an emergency overflow, you do not strictly need to buy a premium V90 UHS-II SD card.

The highest video requirement on the D850 is 4K UHD at 30p, which generates a maximum bitrate of 144 Mbps.

Because 144 Megabits equals exactly 18 Megabytes per second, a standard V30 UHS-I SD card is more than fast enough to record 4K video without dropping frames. If you are on a budget, buy a CFexpress Type B card for Slot 1, and save your money by putting an inexpensive V30 card in Slot 2. But make sure to configure the dual slot behavior so as not to fall into the bottleneck trap I mentioned above!

Formatting and card prep

It is best practice to always format your memory cards inside the D850 before a shoot to ensure the file system matches the camera’s exact folder hierarchy.

You can find the standard format tool in the yellow Setup Menu:

Wrench Icon > Format memory card

You can also use the two-button shortcut by holding down the Mode button and the Delete button (both have small red “Format” labels next to them) simultaneously.

If you accidentally format the wrong card in the field, stop shooting immediately. As long as you have not overwritten the memory sectors with new data, you can usually recover your deleted photos using a desktop recovery tool later.

If your SD or CFexpress card begins to act sluggishly or throw read errors over time, formatting it in the camera may not be enough. You should connect the card to your computer and execute a full format instead of a quick format using a dedicated utility tool to properly wipe and restore the drive.

Notes & References:

1. Note on CFexpress Compatibility: Nikon originally launched this camera with an XQD-only memory card slot. Compatibility with the much faster CFexpress Type B format was added post-release via a major firmware update. Since that initial unlock, Nikon has continued to release subsequent firmware patches to expand the list of officially supported CFexpress cards and improve overall write reliability. Ensure your camera’s firmware is fully up-to-date before purchasing a CFexpress card. [↩︎]