The latest generation of 4K cameras and high frame rates is really pushing the transfer rates of many existing SD cards. All manufacturers are currently in the process of launching the next generation of SD and Micro SD cards that can meet the demands that video is putting on them.
Samsung’s latest SDXC Pro+ 64GB SDXC cards claim to have a write speed of 90MB/s, with a read speed 95MB/s. We tested the card using Blackmagic Speed Test and a Apple Macbook Pro and found that whilst the card didn’t quite match the quoted Samsung speeds for a 1GB and 5GB stress test, it is still very fast.
There is very little variance in either the read or write speed, only around ± 2MB/s, with the speeds averaging around 79MB/s for write and 87MB/s for read, which is a write speed of around 600mb/s.
The Micro SDXC UHS-I U3 card had very similar performance, which is impressive for a Micro SD card. Using the same Blackmagic Speed Test we found the card to have the same write speed of around 79MB/s and a read speed of around 86MB/s, virtucally identical to the full size card. This should be fast to enough to cope with 4K on most of the current consumer cameras that are entering the market.
However, we tried the cards in a Blackmagic Pocket Cinema camera shooting ProRes HQ at 1920x 1080 and found that the cards did start to drop frames, though it was fine using the lower bit rate ProRes Proxy modes.
Another thing to note is that the cards will not work with the Sony A7S II and A7R II cameras. Although they meet the required specification, the cameras fail to recognise them as U3 specification, however, other U3 cards we used were fine, so it would appear to be an issue with the Samsung cards themselves.
Overall the read and write speeds of both cards are fantastic, however, I would recommend trying the cards beforehand if you intend to use them in a camera with a very high data transfter rate, just to be on the safe side.