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Memory card - what types, how to choose

The owner of any gadget sooner or later has a desire to increase his memory. Fortunately, most often this opportunity is thanks to memory cards. Tablets, smartphones, e-books, camcorders, cameras - this is not a complete list of devices, most models of which have a slot for a memory card. You may need a memory card not only to increase the device's memory - in some cases, copying a file to a memory card is the fastest and easiest way to exchange information with other devices.
The algorithm for choosing a memory card for a specific equipment is unambiguous and seemingly quite simple:

  1. Decide on the form factor of memory cards.
  2. Determine the minimum speed required for the gadget to operate
  3. Choose the amount of memory card, based on the needs and financial capabilities.
Unfortunately, in reality everything may not be so simple, because only the speed of the card can be described by as many as four different parameters. Therefore, before proceeding with the choice of a memory card, you should figure out what parameter is responsible for.

Memory card specifications

Form Factor

The standard of the card, describing its size, number, location and purpose of the pins is primarily determined by the gadget in which the card is supposed to be installed. Usually, next to the memory card slot, there are markings for which cards this slot is intended for. And of course, a complete list of supported memory cards will be given in the gadget's user manual.
There are many form factors for memory cards, but the most common today are:

Speed class

The speed class of a memory card determines its speed performance. Most often, from the class, you can find out the minimum recording speed - this indicator is very important for cards on which video is recorded in real time. Speed ​​class mismatches can result in frame drops and recording errors. There are several standards for the designation of the speed class.
SD (microSD) cards have four speed levels of Class 2, Class 4, Class 6 and Class 10. The class is indicated by a number inside the letter "C"and corresponds to the minimum write speed (in MB/s).
For a Class 6 card the minimum write speed will be 6 MB/s. SDHC and SDXC cards can support the UHS (Ultra High Speed) protocol. UHS speed class is indicated inside the letter "U"and corresponds to the minimum write speed in tens of MB/s. A card with UHS Speed ​​Class U3 will have a minimum write speed of 30 MB/s. There are also specifications for Video Speed ​​Class - (the minimum speed in MB/s is indicated after the letter "V") and Application Performance Class, denoted by the letter "A"and has a minimum write speed of 10 MB/s.
The latest version of SDHC / SDXC cards with support for the UHS-II protocol has an additional row of contacts on the case and read / write speeds up to 300 MB/s.
MS PRO DUO cards provide a minimum write speed of 4 MB/s.
JetDrive Lite cards provide a minimum write speed of 60 MB/s.
XQD cards provide a minimum write speed of 125 MB/s.

Since the read speed is usually much faster than the write speed, manufacturers sometimes indicate the read speed class as a multiplier (similar to CD-ROM speeds), with 1x = 150 KB/s. That is, a card with a speed of 133x will have a read speed of 133 * 150/1024 ≈ 20 MB/s, and 1067x - 156 MB/s. Manufacturers often also indicate maximum read and write speeds - they can be many times higher than the corresponding values ​​obtained by the card's speed class. But it should be understood that such speeds are achieved under ideal conditions, in fact, the speed will always be lower, sometimes by several times.
Therefore, when choosing a card, you should be guided by the minimum write speed, and take other speeds as additional information.

When choosing a memory class, you should be guided by the requirements of the device for which the memory card is purchased. For example, if the device does not support the UHS protocol, there is no point in buying a card with a U3 class - it will not work faster than C10.

Card size

The size of the memory card determines how much information will fit on it. On the one hand, the more memory the better. On the other hand, larger cards are more expensive. In addition, the maximum capacity of memory cards on many devices is limited to a value less than the maximum capacity of a card of a given format. The device, for example, can support SDXC cards, but have a maximum memory card capacity of 128 GB. There is no point in buying a 256 GB SDXC card for this device. Such subtleties should be clarified before purchasing in the instruction manual of the device.

Memory card options

If you need to increase the memory of your smartphone by 2-8 GB, first of all you should make sure that it has such an opportunity. If there is a memory card slot, most likely it is designed for microSD cards. An inexpensive microSD card 2-4 speed class is suitable for a smartphone.Progress does not stand still, some modern smartphones can record videos in FullHD quality. So that the video quality does not deteriorate during recording, it is better to choose a card with a higher class: 6-10.
Most e-books support cards up to 32GB. A card of this size and speed class 4 will allow you to build an impressive library at an affordable price. You just need to decide on the form factor: SD or microSD.
For action cameras recording in FullHD format, the best option would be a speed class 10 card (or U1) with a volume of 16-32 GB.
If you are going to use the card as a hard drive for a tablet or laptop, choose from high-speed SD or microSD cards with capacities of 128 GB or more.
To expand the memory capacity of your MacBook Air or MacBook Pro (up to 4th generation), you can use JetDrive Lite, a special design for Apple laptops. Specify the specific type of card in accordance with your laptop model.
If you are a professional photographer and often take RAW burst shots, you need a high-speed card. CompactFlash or XQD - depends on your camera model.