Comments

john_dennis wrote on 9/28/2015, 8:02 PM
Fast enough is fast enough unless the camera manufacturer refuses to write to a card that doesn't meet their requirements as in the case for the Sony RX10ii. The general standards for the SD cards are linked in this thread.

The best course is to read the camera documentation. Speed Class 10 cards have worked for me for 1080, except where the manufacturer refuses to let the camera even attempt to write to a card as in the Sony above which will write 1080-60p to a Speed Class 10 card but will not write 4K unless the card is self-identified as a 64GB SDXC U3 card.
PeterDuke wrote on 9/29/2015, 7:18 PM
Note that SD cards have different read and write speeds. Write speed is the key one for recording, but the faster read speed is the one manufacturers brandish about.

See https://www.sdcard.org/developers/overview/speed_class/

Class 10 means at least 10 MB/s = 80 Mbps write speed.