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Recording work and data in the form of thousands of pictures or hours of video is made possible by compact memory cards. These devices are the standard for photo and movie storage, saving and protecting your files until you can transfer them safely to a more permanent home on your computer or external hard drive. They are available in an array of different types, with a broad range of capacities and data-transfer speeds.
Card Types, Capacities, and Speeds
The various card types include CompactFlash (CF), Secure Digital (SD), microSD, Memory Stick (MS), XQD, SxS-1, SxS PRO+, P2, and microP2. They differ in form factor and the type of interface they use. Across types and within the same type, cards are differentiated by capacity, read speed, write speed, data protection capability, and durability.
Currently, memory card capacities stretch across a broad range, from 2GB to 512GB, and the technology allows for 2TB of maximum storage. Speeds are typically listed in MB/s or Gb/s, and many cards also feature an “x” rating, such as 400x or 1000x, which is used as a shorthand for speed and often appears as part of the name of a card, allowing for quick and easy comparisons of different models (the higher the rating, the faster the card). The “x” represents the standard 150KB/s data transfer rate of a CD-ROM drive. Multiplying this by the number preceding the x in a card’s rating will tell you that card’s maximum transfer speed.
CF cards exist in both Type I and Type II formats, although the smaller Type I, which draws less power and is exclusively a type of flash media, is much more common. CF cards are larger in size than SD cards and are known for their physical durability. To denote transfer speeds, they use the Ultra Direct Memory Access (UDMA) mode system, in which a number of 0-7 gives you a rough idea of how fast a card will be. Mode 0 permits up to 16.7MB/s and Mode 7 allows for up to 167MB/s. CompactFlash cards often feature the x rating in their names, helping you compare speeds at a glance before getting a more in-depth look, by examining the actual data transfer rates.
Secure Digital (SD) and microSD
Among SD cards, the Secure Digital Extended Capacity (SDXC) models have the greatest amount of storage space at more than 32GB, and up to a theoretical 2TB, while Secure Digital High Capacity (SDHC) and SD cards hold up to 32GB and 2GB, respectively. The microSD cards are physically smaller, though they can still feature large capacities and follow the same SD/SDHC/SDXC naming scheme.
SD cards, including the micro type, are divided into classes—2, 4, 6, and 10—where the class number denotes minimum write speed. Class 2 means a minimum of 2MB/s write, while Class 4 means 4MB/s, and so on. The Ultra High Speed Class 1 (UHS-I) rating was established when cards became faster and it was possible for minimum read/write rates to exceed 10MB/s. Now, UHS-II cards offer substantially quicker transfer rates than ever before.
UHS-I and II cards are capable of huge performance boosts over standard cards, in terms of maximum read/write speeds. A UHS Class 1 rating tells you that the technology allows for speeds of up to 104MB/s. Many UHS-1 cards deliver read/write rates of 80―95MB/s, with a lot of others getting up to about 60MB/s. UHS-II denotes even faster maximum speeds of 312MB/s, with the reality being 250―280MB/s for the current SD lineup.
Memory Stick (MS)
A proprietary memory type used in many Sony devices, Memory Stick PRO Duo cards are similar in size to SD cards and are smaller than the original incarnations of the Sony Memory Stick. The MS PRO-HG Duo offers performance approximately four times faster than the PRO Duo. MS cards also have MagicGate copyright protection technology, which provides authentication and content encryption and decryption to prevent unauthorized copying, and conform to Secure Digital Music Initiative (SDMI) standards.
XQD cards, made by Lexar and Sony, use the PCIe interface featured on certain computer expansion cards. In theory, the XQD format has a maximum possible capacity greater than the 2TB limit of other memory card types, though we have yet to see an actual card approaching such massive storage capabilities. They are currently available in several classes: the standard XQD, also known as the H Series, as well as the N, S, and G series. The H and N class support transfer speeds up to 125MB/s, while the S-series supports up to 180MB/s for reading and writing. The newest class, the G series, supports transfer speeds up to 400MB/s to benefit 4K video recording and high-resolution still shooting bursts.
Sony's SxS-1 and SxS PRO+ cards were created for the XDCAM EX camcorders and feature the same interface as a computer ExpressCard. SxS-1 cards feature similar performance compared to the PRO+ versions and offer maximum read speeds of 1.2Gb/s (150MB/s), with slightly lower write speeds. SxS PRO+ memory cards support write speeds of up to 1.5Gb/s (187.5MB/s) and maximum read speeds of 1.6Gb/s.
P2 and microP2
Designed for full HD and 4K recording in Panasonic's P2 camcorders, the company's P2 cards have the same maximum transfer speeds as the SxS-1 cards. The microP2 version, which has a form factor identical to a full-size SD card, is UHS-II and features much faster 2Gb/s (250MB/s) rates. To help ensure high reliability, both the P2 and microP2 cards offer a RAID-type error-correction system similar to that of many external computer drives.
Most consumer-grade cameras and camcorders are compatible with CompactFlash (CF), Secure Digital (SD), or Memory Stick type cards, and several cameras now feature dual memory slots, allowing you to use up to two cards at a time. Common combinations include two SD slots or one CF and one SD slot, along with a handful of different combinations.
The microSD cards are often used in more compact devices, such as smartphones and tablets, though they also fit into a number of small point-and-shoot cameras. They can be adapted through the use of a standard SD-size adapter to function in devices that only accept SD cards. All cameras and other devices that support SDXC cards are also backwards compatible with SDHC and SD, and devices that support SDHC will also support SD cards. The same rule does not apply in reverse, though, and devices compatible with up to SDHC cards will often not support SDXC memory cards.
The vast majority of cameras that take CF cards accept Type I only. Type II is rarely used anymore, but can still be found in certain hard drives and other computer devices.
Before making a decision, make sure you are working within the limits of your camera or other device. Many entry-level and intermediate-grade cameras are not capable of supporting cards with capacities over 64GB.
Use and Applications
Choosing the Correct Capacity
It’s easy to think that bigger is better when it comes to capacity, but it really depends on the application. Many photographers prefer several lower-capacity cards to a single high-capacity one, because that way, if one breaks or fails and work is compromised, they still have the data they’ve saved on the other cards. Another advantage to this approach is that when traveling, photographers can use one card per day to keep a succinct and orderly record of which day’s images are on which card. Those who shoot high-speed bursts, such as sports photographers, and those who record lots of video, often prefer one card with lots of storage space, since it allows for more continuous shooting without having to stop and switch to a new memory source.
Another consideration when deciding upon card capacities is the type of files you shoot, generally, and how large your average file size is. If you are working with a small 12MP point-and-shoot camera and only shooting JPEG files, you can record upwards of 8,000 images to a single 32GB memory card. But if you are dealing with a full-frame DSLR and recording both RAW and JPEG file types simultaneously, you might only get 500 or so images per 32GB.
It’s not just about how much data your card can store, but also how fast it can store and move it. Time-saving is a ubiquitous concern nowadays, and cards with faster write speeds will enable you to get more shots in a given period of time, while higher read speeds will improve workflow efficiency by speeding up card-to-computer file transfers.
Faster write speeds enable improved performance during 4K and HD video recording and RAW and high-resolution JPEG image capture, especially in continuous shooting modes, and when using advanced modes like slow-motion recording. You will experience less lag and fewer interruptions with speedier cards, and this makes a world of difference when recording high-definition movies or fast-action photo sequences.
UHS-1 is really a must for pros using SDHC/SDXC, while those who use CF cards ought to go for UDMA 6 or higher. The XQD card format is designed specifically for transferring large files quickly, as are Sony's SxS-1/SxS PRO+ and Panasonic's P2 cards. Since the microP2 is UHS-II and features 2Gb/s (250MB/s) transfer speeds, it is ideal for professional broadcast video capture.
Unless you’re shooting very casually and are really not concerned about speed, we recommend that you choose a card with read and write speeds of at least 30MB/s. If you’re a professional working with today’s high-resolution cameras, try for at least 45―60MB/s. And if you’re a sports shooter or a 4K HD videographer, get the fastest card you can. Many of the ones on the market today go up to 90MB/s and beyond, and there are offerings that are well over 100MB/s.
Protecting Your Work
Apart from capacity and speed, data protection is a concern. A lot of cards feature Error Correction Code (ECC), which enhances reliability by automatically detecting and fixing transfer errors. This is a great asset in any application, but would be especially important in situations in which you have to work quickly and deliver results in a very short time, such as professional sporting events or news coverage. When you need to upload or send files so that your work can be seen by the world before your competitors’, having a reliable card with a small chance of failure or errors is critical.
Picking a Card that's Built to Last
A card’s durability may also be an important point of consideration. There are really two types of toughness for a memory card: the ability to withstand a large number of insertion/removal and read/write cycles, and the ability to survive environmental factors. Most of the better cards on the market permit 10,000 or more duty cycles as a standard. Those that offer wear-leveling management ensure that data is written evenly across various regions of the card—preventing excessive wear and prolonging card life.
There is a greater degree of variation in the other kind of durability. Certain cards are built to live through bumps, drops, and even heavy burdens that would break or crush most devices their size, while others are designed to last through extremely cold or hot temperatures that would render most electronics useless. There are cards that are water resistant, and even those that are completely waterproof. Additionally, some models are built to survive exposure to magnetic fields and X-rays.
If you’re a travel photographer, such as a photojournalist, or just an avid explorer or adventurer who loves shooting in extreme locations such as the mountains, tundra, jungle, or desert, these tough cards are made for you. Fortunately, some of the real rough-and-tumble cards also feature very respectable speeds—up to 90MB/s or greater for read and write—so you can get the benefits of their strong build quality without having to compromise in other areas of performance.
Whatever your needs, B&H has you covered with a comprehensive array of options spanning all memory card categories.