Some cameras use Compact Flash (CF) memory, but most point and shoots, compact cameras, micro four thirds cameras and even some DSLRs use SD cards. They are also used in many cell phones, GPS units and other electronic devices.
Since CF cards have been around longer, most photographers are familiar with them. But when I ask photographers detailed questions about SD cards, I find there’s some information commonly missing. So this is a quick and dirty SD primer. I think these are the five MOST important things to know about SD cards.
1. There are several types of SD card.
SDSC is the oldest and original format for SD cards. These cards are slower than most new SD cards, but very inexpensive and reliable.
SDHC are high-capacity SD cards that typically get better speed ratings and hold more data – up to 32GB. They typically cost more tan SDSC cards and are generally very reliable.
SDXC cards are the newest SD format (used in cameras) and offer much larger capacities than SDSC or SDHC. SDXC will hold up to two terabytes of information. Although a 2TB card would be very expensive (as in it would probably cost more than many of the cameras it fit in.) They tend to be more expensive and faster than the other two formats and are well-suited to shooting HD video or high-frame rate cameras.
There is another format called SDIO but it is not used in any popular camera that I am aware of.
2. SD cards are rated several ways, depending on the manufacturer. A “Class 2” card offers 2 MB/sec maximum transfer speeds. A “Class 6” card offers 6 MB/sec maximum transfer speeds. Etc. But these ratings don’t tell the whole story. There are other ratings such as UHS Class 1 or Lexar, Kingston and other manufacturers’ “X” rating such as “600X” cards. Suffice it to say that relying on manufacturer speed ratings is always a slippery slope. Some offer read speeds only. Some write speeds only. Do your research and dig in behind those ratings before you make a decision. As with all things, you get what you pay for. The more expensive cards tend to be faster.
3. Not all SD cards perform equally well in all cameras. This is especially true of older cameras. For instance, for a long time, Nikon shooters got better performance out of Lexar brand memory cards than they did other brands. But this distinction is becoming less important. There are still differences between performance. But often times, the differences are so tiny that it puts you into “pixel peeper” land to care. Just know that some cards may perform better on your camera better than others. Feel free to do your own real-world tests and prove this out.
4. Certain card vendors have enhanced their SD cards with features like integrated WI-FI, multiple colors, pre-loaded content or “super information.” In most cases these are gimmicks (except for the Eye-Fi WI-FI cards) and something I recommend avoiding.
5. Here are some miscellaneous things to know about SD cards. It’s best to format them in the camera not the computer. It’s best not to share cards with photographers using different cameras. SD cards are small, easy to misplace and fragile compared to CF cards. Treat them gently to get best results. Some of the newer cards may not work in older cameras, especially the high-capacity cards. Not all cards can be natively read by all computers.
Since many of you will ask me what I use I will share that information in advance. But please realize these cards may not be the best choice for you (see above – not all cards preform identically in all cameras.)
Currently, I am getting the best results out of the SanDisk Extreme Pro 64 GB SDXC Class 10 UHS-1 Flash Memory Card 95MB/s SDSDXPA-064G-AFFP. Your mileage may vary.
(Please note: This is not a white paper nor is this a technical guide. For more detailed information on SD cards check with the SD Association.)