When imaging fully enters the digital age, imaging devices such as smartphones, motion cameras, drones, and dash cams emerge like mushrooms after rain, and TF cards have also become mainstream storage devices. But in the impression of many people, TF cards can be blindly ordered as long as the capacity meets their needs. Therefore, it is either a waste of money to buy high-end products, or to save money to buy mid to low end or even miscellaneous products that cannot fully utilize the device's performance. It can be seen that how to choose a TF card that suits oneself is also very knowledgeable.
At present, mainstream photography and video equipment on the market use standard SD cards and TF cards (Micro SD) as storage devices. The former is mostly used for professional equipment such as DSLR cameras and camcorders, while the latter is widely used for various digital devices such as smartphones, sports cameras, and drones due to its small size. In recent years, storage manufacturers have increasingly focused on the universality of storage cards, and the combination of TF cards and SD adapters (commonly known as adapter) has gradually become the mainstream in the market.
With the popularity of high-resolution and high bitrate video images, in addition to capacity, these imaging devices also have higher requirements for TF card performance. So, how to quickly understand the various performance parameters of a TF card? Observant friends can notice that the front of the storage card is basically labeled with all the information, such as the Star 128GB TF card below, with the number 128 indicating a capacity of 128GB. In addition, there are also Micro SDXCI, U3, A2, V30 and other identifiers, which are the type and speed certification information of this TF card. Let's interpret these contents below.
MicroSDXCI refers to the type of card, Micro refers to the TF card (Micro SD card), and without the word Micro, it is a standard SD card. SDXC indicates that the capacity of the card is above 64GB, and if the card surface is marked as SDHC, the capacity of the card is below 32GB. The Roman numeral I after SDXC is written entirely as UHS-I, representing the bus interface speed, which is 104MB/s.
U3, V30, A2 refer to the speed level of this TF card, and earlier products can also see the C10 logo. From the content of the figure below, it can be seen that the higher the values of U, V, and C, the faster the continuous writing of this card. For example, the minimum continuous write speed of U3 is 30MB/s, while the minimum continuous write speed of U1 is 10MB/s, which is consistent with C10. Therefore, many U1 specification TF cards now have the C10 label removed; And V represents the video speed level, for example, V30 corresponds to a minimum write speed of 30MB/s, which can support shooting 4K 30FPS videos, V60 can support shooting 4K 120FPS videos, etc.
The A2 label is the read and write speed standard specified by the SD card association, which is an association certification that measures whether the storage card can meet the basic conditions of application use. There are two levels, A1 and A2. The continuous read and write speed of A1 level is the lowest 10MB/s, and the random read and write performance is 1500 and 500 IOPS; The continuous read and write speed of A2 level is the same as A1, but the lowest random read and write performance is 4000 and 2000 IOPS. Therefore, A2 has stronger random performance than A1, and has an advantage in reading and writing a large number of small files.
The front of current TF card is printed with multiple speed level markings, and the fastest one is sufficient. Of course, this speed level also represents the lowest speed, and the highest write speed will test the technical strength of the storage manufacturer. For example, the highest speed level of the 128GB TF card above is UHS-I, and the measured highest read and write speeds can reach 91MB/s and 56MB/s.
The above only explains the basic information of TF cards for everyone. When choosing, in addition to meeting the capacity requirements, it is also necessary to start from the actual needs and usage scenarios of imaging devices.
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