Buying a SD Memory Card

So, which all parameters do you think the most critical when buying a SD memory card?  Most of us feel that the Brand and the memory capacity are the only 2 important things to make the buying decision. Unfortunately, this is not true.

What to look out for?

In addition to the brand and the memory capacity, there exist 2 more parameters which play a very crucial role in determining the correct SD card for your use. Like any other media, SD cards vary in their read/write speed which is very important when capturing audio or video. The read/write speed of the SD memory card is expressed in 2 ways:

1. Speed Class

Class of the SD memory card identifies its minimum write speed. As of now, SD card comes in four different classes: Class 2, Class 4, Class 6 and Class 10. Thus, a class 2 SD card can write data at minimum speed of 2 MB/s. Remember, the class identifies the minimum speed and not the actual rate at which the data can be written. Thus, a class 2 SD card can write data at a speed of 15 MB/s also, but not less than 2 MB/s.

2. Commercial X Rating

This is comparatively an older way of expressing the memory card speed (such as 100x, 200x, etc.). In X rating technique, 1X is equivalent to the initial standard CD-ROM speed of 150 KB/s. Remember, X rating speed determines the maximum data transfer rate of the memory card.

Happy shopping!

References:

http://www.lexar.com/files/product/datasheet/White_Paper_SD_Class_xRating_updatedUHS_Final_1.pdf

http://www.lexar.com/files/product/datasheet/Understanding_SD_Association_Speed_Ratings_122010.pdf

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