Making Sense of Memory Cards

Selecting a memory card might seem like a complicated process, but knowing some key pieces of information can help make selecting the right memory card easy. In addition to understanding the different memory card formats and related terminology, photographers and videographers must also consider their use case and workflow to ensure they choose the right technology to meet their needs.

Common Memory Card Formats
While many memory card formats have come and gone over the years, two formats have remained popular options for different types of shooters: Secure Digital (SD) and CompactFlash (CF).

Secure Digital is the most popular memory card format in the world today. SD cards can be found in all types of cameras, from point-and-shoot still cameras and handheld video cameras, all the way up to professional DSLRs that capture images and video. The mobile versions of SD cards are microSD cards. They adhere to the same technical specifications as their SD card big brothers, but are designed for use in smartphones and tablets. As image capture devices have transformed over the years, becoming smaller and more portable, the microSD card has been adopted for use in new technologies like HD sports camcorders and aerial cameras.

The second longstanding format is CompactFlash. CF cards are generally preferred by professionals for their physical durability and size, and are used in professional DSLRs and cinema cameras.

Understanding Memory Card Terminology

In addition to recognizing the different types of memory cards available, there are a number of symbols and terms that help identify the type of memory card, as well as its capacity and performance capabilities. When reviewing these details, it’s important to understand your use case and workflow to help determine which card is best for you.

  • Capacity: Like flash drives, hard drives, and solid state drives, memory cards have specific capacities which are identified in gigabytes (GB) and labeled on the front of the card. The higher the capacity, the more content (photos or videos) you can store on the card. So if you primarily shoot still images while hiking or camping, you might not need a memory card with a huge capacity. But if you’re planning to shoot a lot of video content, you should opt for a larger capacity card.
  • x-speeds: The “x” identifier was originally adopted by Lexar and since implemented by many card brands in the industry. The higher the number before the “x” speed symbol, the higher the performance of the memory card. Each “x” represents .15MB/s. For example, if you multiply our SD 2000x by .15MB/s, you will get 300MB/s.
  • Performance: A card’s performance is defined as the speed at which your card is able to store and unload images, expressed as “write” and “read” speeds.
    • Write speed: Write speed is how fast images are written to a memory card inside the camera.
    • Read speed: Read speed is how fast images are transferred off of a memory card to a computer.
  • Speed Class: SD cards have additional symbols to define speed, which can be found on the card label. Designated by the SD Association, a global association that sets industry-leading memory card standards for SD formats, speed class symbols show photographers the required minimum write performance. There are two kinds of speed indications regarding SD cards – Speed Class  and UHS Speed Class.
    • Speed Class: Designates minimum write performance to record video. These range from Class 2 (slowest) to Class 10 (fastest).
    • UHS Speed Class: Indicates how quickly video content can be transferred onto the memory card. UHS-I enables maximum transfer speeds of 104MB/s while UHS-II enables maximum transfer speeds of 312MB/s. Within the UHS Speed Class there are two designations, U1 and U3, which represent minimum write speeds of 10MB/s and 30MB/s respectively.
  • Video Performance Guarantee (VPG): VPG comes from the CompactFlash association and is very similar to SD’s speed class. Today, VPG has two ratings which indicate the minimum write speed the card can perform, VPG-20 and VPG-65, with writes speeds of 20MB/s and 65MB/s respectively.

Emerging Memory Card Formats
In addition to SD and CF cards, there are a few emerging memory card formats that you might not be familiar with just yet – XQD and CFast – both published by the CompactFlash Association. It’s worth noting that these new formats were created to replace the CF card format as it had reached maximum performance capabilities and cannot meet the intense write speeds today’s camera technology demands. In its current revision, 2.0, XQD cards have a theoretical limit of 500MB/s. CFast in its current revision, 2.0, has a theoretical limit of 600MB/s. Both of these card formats are ideal for shooting 4K video and beyond with professional-level, cinema-quality cameras.

Questions to Ask When Buying a Memory Card
Now that you understand the different types, speeds, and classifications of memory cards, how do you determine what card is best for you and your needs? Here are a few questions to ask yourself before you purchase your memory card:

  • Type of photography: What type of photographs do you plan to take? Action shots, still shots, or even video? Understanding how you plan to use your memory card to capture images and video will help you decide what performance level and features are most important to you. Shooting stills like portraits or landscapes don’t necessarily require fast write speeds. Adversely, capturing action, sports, or video requires fast write speeds to help eliminate missed shots or dropping frames from video. Beyond write speed, opting for a faster read speed means you will be able to offload your content quicker, resulting in a more efficient workflow.
  • Image format: Do you shoot in JPEG, RAW, or both? RAW images take up more room on your card than JPEG files. Therefore, you will need a larger capacity card if shooting RAW images, or RAW and JPEG images at the same time.
  • How much and how many: How long do you plan to shoot? Answering this question will help you determine how much storage (capacity of the card) and the number of cards you will need. We recommend always having at least one extra memory card on hand when shooting, in case you decide to shoot more than you’d originally planned. It’s always better to have too much storage than not enough!
  • Last but not least, memory card readers: Investing in a solid memory card reader from a reputable manufacturer is key for post-production work. Buying the fastest card on the market won’t do you any good if you have a slow reader. If your computer has a USB 3.0 port, buy a USB 3.0 reader to take advantage of fast read speeds. It’s important to note the difference between USB 2.0 and USB 3.0 can mean cutting transfer times down from hours to minutes. Transferring your content faster lets you start editing sooner, which in turn allows you to more quickly shift your focus back to shooting.