UHS-II: Camera list and short explanation
Even we who write about and work with SD memory cards almost daily sometimes having problems with keep track of all new standards and technologies. Below is a brief explanation on the subject of UHS-II and a list of system cameras (DSLR and DSLM) that have at least one UHS-II memory card slot.
What is UHS-II basically?
UHS stands for Ultra High Speed and is the name of a comprehensively defined interface for SD memory cards. The first revision, UHS-I, allows transfer rates of up to 104 MB/s, UHS-II triples that to up to 312 MB/s. A huge step compared to just 25 MB/s that non-UHS cards support.
To achieve these much higher speeds, SD and microSD memory cards with UHS-II and also future UHS-III cards have a second row of contacts (pins 10-17; see picture below). The new contact row is obviously not available and therefore not used in older cameras without support for UHS-II/III. The separation ensures compatibility with millions of existing cameras, card readers, smartphones, tablets and the like, as the first, upper contact row remains as a fallback.
You wanna use your decade old, non-UHS SD card in a brand new camera with an UHS-II interface? No problem. You bought an ultra fast UHS-II SD card and wonder whether you can also use it in your old camera? It almost certainly will. Just check if the older camera is compatible with high-capacity SD cards (e.g. SDXC for >32 GB). But keep in mind that only the combination of an UHS-II card and camera (or reader) will unlock UHS-II speed.
TL;DR: UHS-II/III is completely upwards and downwards compatible. Experience has shown that UHS-II memory cards work without problems even in cameras and smartphones without any UHS support at all, and modern cameras with UHS-II interfaces also work with slower SD cards without UHS-II functionality.
UHS-II enables three times higher transfer speeds than UHS-I and even over 12x higher speeds than memory cards without a UHS interface. Thanks to modern technologies, even without higher power consumption (compared to UHS-I).
An important remark on UHS-II cameras
Not all UHS-II cameras were built equal. Depending on the chipset and firmware used, the real-world performance varies. Quite a lot. For instance, the Panasonic Lumix GH5 reaches just ~90 MB/s, the Canon EOS R5 whopping 250+ MB/s.