The cold knowledge you do not know – how to choose a good memory card?
1. Classification of memory card
With the rapid development of digital equipment, later waves are never weaker than the former. Previously, there were a lot of types of memory CARDS, such as CF/SM/MS/MMC/SD/XD/ etc., but now, there were only a few types left. Referring to the following pictures, we can have a basic understanding.
（from the top to bottom, there are Compact flash-CF, Secure Digital SD, Micro SD- commonly known as TF)
CF card: It can be judged by the label value on the card surface, as shown in Figure 160MB/s, which refers to the maximum transmission efficiency - the size of data can be transmitted per second, but now most manufacturers do not indicate whether it is writing effect or reading efficiency. Generally speaking, writing efficiency is lower than the actual efficiency, most of manufactures use maximum reading value as a promotion.
Additionally, UDMA logo represents the interface standards, and people can distinguish them by 5/6/7, the higher the numerical value represents better version, whose transfer rate is better.
SD/Micro SD: the SD card and Micro SD belong to the same family, so they have the same standard and are divided into two types of speed markers, as shown in the figure below. Divided into speed grade (marked with C) and UHS high speed grade (marked with U), they represent the minimum write efficiency, such as C4, which means the minimum write capacity is up to 4MB/s, but the U mark will generally appear, following the unit of speed.
3. Computers require card reader to read memory card. Some computers have built-in card reader, but there are still many computers needs an external USB card reader. If the card reader’s version is too old, it will reduce the speed of transmission speed and copying files. When choosing card readers, we must choose USB3.0 interface and USB3.0 version, because USB 3.0 has a transmission rate of 5Gbps, which can satisfy the current memory card transmission. If you use a USB 2.0 card reader, especially when you copy a large number of photos, it will become very slow.
Generally, We can see the SD/SDHC/SDHC logo on the card face. What's the difference among SD and SDHC and SDXC CARDS? SD CARDS, SDHC CARDS, and SDXC CARDS differ in their specifications. SD CARDS support 2GB capacity at most, SDHC supports up to 32GB capacity, and SDXC supports up to 2TB(2048GB) capacity. Digital devices supporting SDXC CARDS are compatible with SD CARDS and SDHC CARDS. If the device only supports SD CARDS, it is not compatible with SDXC, SDHC CARDS. Therefore, when we choose a memory card or card reader, we must choose one with SDXC logo. This supports the maximum capacity.
5. what are the different uses of the above three kinds of memory cards?
CF card: mainly used in some industrial computers, ultra HD cameras, on-board computers and other equipment that need shock-proof high-speed storage;
SD card: mainly used for digital SLR cameras.
Micro SD card is mainly used for smart phone and tablet computer.
Through this introduction, I believe you have a very clear understanding of the common memory cards. If your mobile phone supports more than 1080p video, it is recommended that at least C10 or more memory cards be required to avoid getting stuck and no response from APPs installed in the memory card. If you choose SD memory card for digital SLR cameras, it is recommended to use the specification above U1. Carefully check the maximum fetch speed and write-read speed that the memory card can provide when purchasing to avoid buying memory card, which is not fast enough to meet your need. I hope this article will make you get more skills.