Types of Camera Memory Cards

There have been a surprising amount of different memory card formats used in cameras. Card formats are often revised multiple times to increase speed and capacity. This can quickly become confusing.

The process doesn’t appear to be stopping either. High megapixel cameras and high frame rate 4k and 8k video recording, keep pushing the limit of transfer speeds.

Memory card types of been ordered by how common they are.

Compatibility can be confusing because there are many types of SD cards. Backwards compatibility is very good. However, there are two common problems people run into with SD card compatibility that can cause camera errors.

The first problem is using a newer card than a camera (or device) is able to support. Cameras will not be able to format a newer SD card, because that card is larger and uses a different standard to access the memory. For example trying to use an SDXC card in a camera that is only compatible with SD and SDHC cards.

Older cards in newer cameras is the second problem. Older cards often have much slower read and write speeds than what is currently available. In order to record video a SD card has to have a continous write speed that is faster than the bitrate the camera is outputting. Continous shooting can also be effected because the camera image buffer will take a long time to clear.

There are too many rating standards and acronyms to keep track of. I think this was mainly done for marketing as many of the rating standards mean exactly the same thing. It’s why there are icons galore on packaging.

The manual for your camera should list which generation of cards a camera is compatible with. If you don’t have the manual for your website, check the manufacturers website for a PDF copy of the manual. They can answer almost all of your questions about your camera.

Name Capacity File System
SD Secure Digital Up to 2GB FAT12/FAT16
SDHC Secure Digital High Capacity 4GB – 32GB FAT32
SDXC Secure Digital eXtended Capacity 64GB – 2TB exFAT
SDUC Secure Digital Ultra Capacity 4TB – 128TB exFAT

I think these terms helped manufacturers of cameras and memory cards to obfuscate performance.

A camera than can shoot 4k 60fps and a camera that shoots 4k 20fps can both market themselves as being able to shoot 4k video.

The FPS for photos on a spec sheet never makes it clear how quickly a camera’s image buffer will fill up and be cleared. A small buffer can mean you only get a little over a second for burst shooting. For more capable cameras, a slow memory card could turn a camera capable of continously capturing 10+ fps forever down to a crawl.

For memory cards, there’s read/write speeds* and then there is continous read/write speeds. The maximum transfer speed advertised is likely for a small amount of data in favorable conditions.

For continous shooting or video, you want to know what the continous write speed is. The card needs to be able to have data continously written to it faster than what the bit rate of the video the camera is recording.

The initial release of SD cards were set to have a read and write speed on 12.5 MB/s. Next, a High Speed version (25 MB/s) was introduced with the 1.10 SD card spec.

Some SDHC and SDXC cards come with a version of the Ultra High Speed (UHS) bus enabled. There are three different version that allow for increased sustained read and write speeds.

The faster speeds comes at a cost for SD cards and reader. I’m not sure we’ll ever see UHS-III SD cards as there are currently CFexpress cards on the market that are faster than the theoretical UHS-III card speeds.

High end cameras, such as the Sony A7 IV, have settings that can produce video at a higher bit rate than the fastest UHS-II SD cards can write. Don’t sink money into expensive and “fast” SD cards.

Card Type Speed
UHS-I 104 MB/s
UHS-II 312 MB/s
UHS-III 624 MB/s
CFexpress 1 GB/s – 4 GB/s

There are two types that differ by thickness.

  • Type I - 3.3mm thick
  • Type II - 5mm thick

Older cameras can have restrictions on the maximum capacity of the card that can be used. This is because of the file system the camera uses to store images or video on the memory card. Many camera will have an error message and be unable to format a memory card that is too large.

Another common point of failure are bent pins inside the memory card socket of a camera or card reader. You can see all of the hole the pins need to slot into on a CompactFlash card.

Type II interfaces were noteably used for Microdrives. These were 25mm wide mechanical hardrives. They were released in 1998 and used because they could have larger capacities than CompactFlash cards that used flash memory.

Due to their mechanical nature, Microdrives were not very reliable. Shocks from a fall could damage them and render them useless.

By 2006 CompactFlash cards had caught up in terms of capacity. CompactFlash also had faster transfer speeds, better reliabilty, and lower costs, which rendered Microdrives obsolete.

Microdrives were used in some portable audio players, most noteably both generations of iPod mini from 2004 and 2005.

CFexpress cards use the NVM Express (NVMe) protocol over a PCIe 3.0 interface. These seem to be the newest memory card format to be widely choosen by manufacturers for their high end and professional camera models. That is likely because of their far superior performance compared to any other comercially available alternative.

Currently, there are two versions of CFexpress.

Version 1.0 was launched in 2017, uses PCIe 3.0 x2, and has transfer speeds of 2 GB/s.

Version 2.0 was launched in 2019, uses PCIe 3.0 x2, and has transfer speeds of 1 GB/s, 2 GB/s, or 4 GB/s. The speed depends on what they host device supports.

CFast is a variant of CompactFlash. It uses the Serial ATA (SATA) interface rather than the Parallel ATA/IDE (PATA) bus.

The origins of PATA date back to 1986. With SATA being introduced in 2003. For a long time, each of these were used in computers for hard drives and SSDs.

While you can likely find these cards/interface used in embedded devices, cameras have moved to CFexpress.

Uses PCI Express as the interface for data transfer. This standard is also used in computers.

The advantage was faster transfer rates and the ability to have capacities larger than 2TB.

The XQD standard was announced in 2010. By 2016, CFexpress was decided to be the replacement for XQD. In 2018 Lexar announced that it was discontinuing support and production of XQD cards in favor of CFexpress.

Sony has a long history of releasing proprietary media formats. This is done to charge higher prices to their customers for media. Because the standards are not open, licensing fees can also be charged to third party manufacturers of media. Past examples by Sony are Betamax tapes and MiniDisc.

Sony Memory Stick was launched in 1998, the year before SD cards. SD and CompactFlash cards took more marketshare because they were less expensive and often offered better performance.

For a long time Sony was the only company supporting the format. I haven’t been able to find a device that wasn’t made by Sony that uses Memory Sticks as the memory card format.

If you’re interested in strange technological quirks of the past, here’s your answer.

Two 128MB Memory Sticks were fit into one and were controlled by a switch. That’s right, in order to use the card you would have to:

  1. Turn off the camera.
  2. Remove the memory card.
  3. Toggle the switch on the memory card.
  4. Put the memory card back into the camera.
  5. Turn the camera on.
  6. Continue shooting.

Simple! It’s hard to understand why these cards were so unpopular.

Keep in mind that at the time of release these would have been more than twice the price of 2 128MB cards. Using 2 cards removes the step of toggling a small switch. It also gives you physical separation of images so a card failure would in theory only cost a maximum of half your photos.

At the time of writing this the 256MB cards that are 2x 128MB are less than half the price ($26) of two separate 128MB Memory Stick cards($17 x2). My assumption is that people are just buying the cheapest option that is compatible with their camera or device.

Look for the clear purple Lexar 128MB x2 cards.

This revision allowed for a capacity of up to 32GB. However, 2GB was the largest capacity that was manufactured.

This was due to the large physical size of the cards compared to SD and microSD cards.

There are Memory Stick Pro Duo adapters that allow the smaller PRO Duo cards to be used in devices or card readers that use the Memory Stick PRO format.

If you want a 2GB card, my suggestion are the 2GB Sony memory Stick PRO MagicGate cards.

You can get microSD to Memory Stick PRO Duo adapters. If you already have a microSD card that is the correct capacity and faster enough write speed, you can use one of these to potentially save some money.

This was a smaller format meant to compete with microSD memory cards.

Three xD memory cards with different capacities.

eXtreme Digital cards were made by Olympus, Fujifilm, and Kodak. They ranged in size from 16MB to 2GB and were in use from 2002 to 2009 in point and shoot cameras. They were derived from the SmartMedia card.

SD and CompactFlash cards won over xD memory cards. SD and CF cards had faster transfer rates and were using in more than just cameras.

The front and back of a 128MB SmartMedia with a Memorex label.

SmartMedia cards were released in 1995 and used in Fujifilm and Olympus cameras. Their use was limited to early point and shoot cameras from both manufacturers.

Cards are available in 2MB to 128MB in capacity. Expect to pay a premium per MB for the 128MB capacity ones.

There were two different versions 5V and 3.3V. The versions are based on the main voltage that was used. The 3.3V cards are sometimes referred to as 3V SmartMedia cards.

The older 5V cards have capacities of 2MB and 4MB. These cards are rare and worth more than $100 in working condition.

SmartMedia cards were also used in some synthesizers and other audio equipment. Examples are the Roland XV-88, Yamaha S08, Roland MC-09, and Korg Triton LE.

USB card readers can be found. They will most likely be USB 2.0 (60 MB/s) and have USB-A (rectangle) connections. It doesn’t really matter though because the transfer speeds are going to be limited by the SmartMedia cards.

MultiMediaCards were released in 1997, 2 years before SD cards. They are similar in dimensions to SD cards, and many early devices that used SD cards could also use MMC cards.

The largest available capacity I found available on eBay was 1GB. There is the ability to use 2GB MMCmobile cards with an adapter.