Most of the digital camera and camcorder are able to record HD video nowadays. And most of them are using SD card which have SDHC and SDXC standards. The writing speed is very important as you don’t want to miss recording any frame of the video. The speed class rating is based on minimum writing speed of the SD cards. There are class 2, class 4, class 6 and class 10 SD cards in the market now.
SD, SDHC and SDXC Card Speed Class Rating
Class 2 = 2 MB/s
Class 4 = 4 MB/s
Class 6 = 6 MB/s
Class 10 = 10 MB/s
It is very easy to determine SD card speed class rating. For example, class 2 SD card is able to write minimum 2 megabytes per second while class 4 at 4 megabytes per second. Same apply to class 6 and class 10.
Be careful when buying SD card for your digital SLR camera. Most of them require high speed SD card in order to record full HD quality video.