How to choose an SD card for video: V30, V60, V90 and CFexpress

The letters after “SD” say nothing about speed, only capacity and file system. Per the SD Association, SDHC covers over 2 GB up to 32 GB with FAT32, SDXC over 32 GB up to 2 TB with exFAT, and SDUC over 2 TB up to 128 TB, also exFAT.

FAT32 limits a single file to 4 GB, which is why older devices split long recordings into chunks. And note: an SDXC card will not work in a device that only supports SDHC. The reverse is fine.

What about “micro SD vs SDXC”? They are not opposites: microSD is simply a smaller form factor with the same logic and capacity classes (microSDXC). For a camera with an SD slot buy the full size; microSD belongs in drones, action cameras and phones.

The number after the V is the minimum sustained write speed in MB/s: V30 guarantees 30 MB/s, V60 60 MB/s and V90 90 MB/s. That is exactly what a camera needs – a steady stream of data for the whole take, not a short burst. The big “300 MB/s” on the label is the maximum read speed and says little about recording.

Work out the class from the bitrate: divide megabits per second by eight. According to its manual, the Sony α7 IV records XAVC S 4K at 200 Mb/s (25 MB/s) to a U3/V30 card, but XAVC S-I 4K at 600 Mb/s (75 MB/s) needs SDXC V90 or CFexpress Type A with VPG200. Leave some headroom and always check the class in your camera’s manual.

UHS is the bus – the path between the card and the device. UHS-I has one row of pins and tops out at 104 MB/s. UHS-II adds a second row and, according to the SD Association, handles 156 MB/s in full duplex or 312 MB/s in half duplex. You can spot it by the Roman numeral II on the label. The V60 and V90 classes exist only on UHS-II and faster cards.

A UHS-II card also works in a UHS-I slot, but only at that slot’s speed – the manufacturer says the Sony TOUGH SF-M 256 GB reads up to 95 MB/s there instead of 277 MB/s. Before paying for UHS-II, check what your slot supports; some bodies have one UHS-II slot and a second that is UHS-I only.

CFexpress talks over PCIe, like an SSD in a computer. In version 4.0 the Exascend Essential Pro Type A reads up to 1,800 MB/s and the Element Pro Type B 1 TB up to 3,500 MB/s. But you mainly buy one because your camera demands it for top codecs, RAW video or long bursts.

Type A is smaller and uses one PCIe lane; according to the CompactFlash Association only selected Sony cameras use it so far, and their slot often takes SD too. Type B uses two lanes and the XQD form factor; it appears in selected Canon, Nikon, Fujifilm, Panasonic and Sony bodies. The types are not interchangeable, so buy for your slot. For video, check the VPG mark – VPG 400 guarantees a 400 MB/s write.

A fast card in a slow reader is like a sports car in a traffic jam. Cheap readers and built-in laptop slots are often UHS-I only, so they read a UHS-II card at around 100 MB/s. Offloading a full 128 GB card then takes roughly 21 minutes instead of about 7 at 300 MB/s – a theoretical figure, but after a long day you will feel it.

The Exascend UHS-II SD/microSD is a pocket reader with a UHS-II SD slot of up to 300 MB/s and a microSD slot (UHS-I). It weighs 12 g and connects over USB 3.2 Gen 1 with a USB-A plug built into the body, no cable needed. Do not skimp on the reader: while copying, your footage still exists in only one place.

If you shoot on CFexpress Type B and also carry SD and microSD cards from a drone, you will appreciate the SmallRig 4532. It is a reader and a case in one: slots for CFexpress Type B, SD and microSD (both UHS-II, up to 312 MB/s) and a USB 3.2 Gen 2 interface at up to 1,250 MB/s. The cards show up on the computer as separate drives, so there is no need to swap them.

Bear in mind that USB 3.2 Gen 2 holds back the fastest CFexpress 4.0 cards – for their full speed you need a USB4 reader. For most laptops it is a sensible compromise. The case has a USB-C cable tucked into the body, a separate power port, an aluminium heatsink and an AirTag slot.

A fake card reports, say, 256 GB but actually holds a fraction; once full it starts overwriting data, and you only find out in the edit. Buy from authorised dealers, do not trust a suspiciously low price, and before a real job fill the whole new card with a checking tool such as H2testw or F3.

Format the card in the camera you will shoot with, and only after backing up; do not delete files from it on the computer. For a longer job, several smaller cards are safer than one huge one, and on a body with two slots record a backup to both. In the SmallRig case every slot has a sliding empty/full marker, so a full card never goes back into the camera by mistake.

Vlogs, family videos, Full HD and 4K up to 200 Mb/s: a V30 card and a decent reader are enough.

Long 4K recordings, slow motion, hybrid stills and video: the Exascend Catalyst V60 512 GB, or the rugged Sony TOUGH V60 if you shoot outdoors in dust and rain. Pair it with a UHS-II reader.

Intraframe codecs around 600 Mb/s on SD: the Exascend Catalyst V90.

A body with a CFexpress slot: Type A for selected Sony models, Type B for Canon, Nikon and others – plus a reader that does not waste its speed. One rule always applies: camera manual first, card second.