Breakdown of all the Memory Card Options Available for Photographers and Videographers

Memory cards come in all shapes and sizes, and with many cameras offering multiple options for their camera systems. Mainly when dealing with cameras that provide multiple cards supported, it can be a bit confusing to find which one offers the best options for your camera system. For example, camera systems like the Nikon D5 offer two models to choose from when purchasing, the QXD model or the model offering Compact Flash, with each format providing different advantages and disadvantages.

Because of this confusion, we decided we’d write a piece on the various card formats, and their advantages and disadvantages, so that you know which card is best for you for your next rental or purchase. But for we get into the individual card formats, let’s talk about the most important topic – speed.


Perhaps even more confusing than all the card types is how they’re rated for speed. You’d think that with something as universal as data transfer, there would be a universal way of measuring it with a memory card – but you’d be wrong. Many SD cards use a ‘U’ rating system, Lexar has a habit of putting an x in front of an arbitrary number, and only Sandisk is reasonable enough to use an “MB/s” measurement. So with so many ways that they measure speed, how is it all broken down?

SD Cards Measurement (AKA Speed Class Measurement)

When it comes to SD cards, they are measured using the Speed Class measurement, which is a series of arbitrary symbols and numbers that don’t explain one thing or the other. This speed class is usually signified by one of three logos; a C with a number in the middle of it, a U with a number in the middle of it, or a stylized V with a number next to it. While they have a dozen different buses and other symbols (which you can learn more about if you’re interested, by going to SD’s website), the Speed Class is considered a universal system for both SD cards, as well as microSD cards.

Compact Flash Speed Measurement

Where SD cards will often use the Speed Class measurement system, Compact Flash cards have opted to make it even more complicated. With some brands, such as Sandisk, will use a pure maximum transfer speed (ex 120MB/sec), many others choose to use a more arbitrary system (such as saying the card is 1066x speed). While a bit more complicated (and perhaps a bit misleading), when you see an ‘x’ number on a card, you can usually determine the MB/sec read/write speed by dividing that number by 6.666 (or multiplying by 0.15). So for example, if a card is x800, then it’s read speed is up to 120MB/sec.

UDMA Measurement

In addition to using x### speeds, Compact Flash cards will often use a UDMA measurement to determine the read and write speeds for the card. UDMA stands for Ultra Direct Memory Access and is a system to more easily identify the transfer rates on cards. The number following the UDMA is typically between 0-7, and translates to the following —

UDMA 0 – 16.7 MB/sec
UDMA 1 – 25 MB/sec
UDMA 2 – 33.3 MB/sec
UDMA 3 – 44.4 MB/sec
UDMA 4 – 66.7 MB/sec
UDMA 5 – 100 MB/sec
UDMA 6 – 133 MB/sec
UDMA 7 – 167 MB/sec

Brand Importance

One thing worth discussing before we get too involved in this piece is the importance of brand recognition. When shooting, video or photos, all of the data is pushed to the memory card, and not all cards are created equal. Not only are some cards held to a higher standard from production to sales, but many of the larger brands also offer a lifetime warranty on their memory cards. No shoot is worth losing because you wanted to save a couple of dollars on your memory card, so it’s always recommended to buy only trusted brands when purchasing memory cards (and buy only from trusted retail stores, as counterfeit cards do exist and are a growing problem). Of the recommended brands, we recommend Sandisk, Lexar, and ProGrade Digital. And please note, this advice also applies when it comes to selecting your card reader.

Types of Cards

Compact Flash Cards (CF Cards)

CF Card Size Example

Compact Flash cards have been the standard for most DSLR systems since the original DSLR format. Larger in physical size when compared to the other options (such as SD cards), Compact Flash cards are most commonly found on DSLR systems, like the Canon 5d Mark IV, Canon 5Ds/5DSr, and the Nikon D810. However, many of the newer cameras also offer SD slots for their systems, and many others have adapted to the CFast and XQD memory solutions, which have proven to be the future of memory going forward. This primarily has to do with CompactFlash cards being Parallel ATA systems, with the maximum transfer rate of 167 MByte/s.

CFast Cards

In 2008, the Compact Flash Association recognized the potential ceiling of the Compact Flash card and developed the CFast infrastructure as a result. Using a Serial ATA bus, the read/write speed potential was increased significantly, reaching up to 600MB/sec with the CFast 2.0 platform. However, the development and use of CFast has been slow, and many have already decided that the XQD/CF Express platform will take over, and become the new standard in future generations. That said, many cameras support the CFast system, such as the Canon C700, Canon C300, Canon 1DX Mark II, Arri Alexa Mini, and the Blackmagic URSA Mini.

XQD/CF Express Cards

Among the newest and exciting memory card formats, the XQD promises some pretty incredible speeds, while maintaining a small form factor. Only slightly larger than an SD card, the XQD, or also called CF Express with its latest iteration, allows for speeds of 1000MB/sec on the XQD format, and 7880 MB/s on the newer CF Express format. While there aren’t any cameras yet that can take advantage of the full speed of the CFexpress system, the CFexpress is backward compatible with the XQD system, so if you’re going to buy one, you should probably just make it the CFexpress card at this point.


SD Card size Example

The standard for smaller camera systems is the SD card. Developed in 1999, the SD form factor quickly became the most popular memory format, particularly with smaller Point and Shoot and Mirrorless cameras. However, with the original SD format maxing out at a 2GB size, SDHC was quickly developed and shares the same design as the original SD. While SD has long since retired, SDHC is still a relatively common system format and allows for transfer speeds up to 25MB/sec on the High-Speed bus, and up to 312MB/sec on the UHS-III bus. However, at that point, it might be easier to upgrade to the SDXC format, which allows for much faster transfer speeds over the other options.

Whether it’s an SD, an SDHC or an SDXC, it’ll be impossible to tell without looking at the label, as they all share the same size and format. Additionally, camera systems are reverse compatible with these systems (So a camera that supports SDXC will also support SDHC). However, older cameras may not support the newer formats.

MicroSD Cards

Micro SD Card Size Example

Among the smallest in design, MicroSD cards are used on devices that may be too small to hold a Compact Flash or SD card system. Most notably, these cards are found in drones and action cameras, such as the GoPro Hero. There smaller size is nice, but they do come with some downfalls. The first one being that of course, they’re not as fast as the competitors, with the fastest card available having a Read Speed of 275MB/sec, though most of them sit closer to 70MB/sec.

Solid State Drives (SSD)

Whereas up until now we’ve been talking about smaller form factor systems primarily designed for DSLRs and compact cameras, we also see that SSDs are becoming more prevalent in the industry, particularly with video camera systems. Larger video cameras typically use SSDs as their preferred format, but as do digital recorders, such as the Atomos Ninja Inferno 4K, and the Convergent Design Odyssey 7Q+. The SSDs used for these systems are no different than what you might use for your computer, and thus, have a broad range of brands.

Red Mini-Mag

Red Mini Mag’s are RED’s choice for memory solution. Essentially just branded SSDs, the Red Mini-Mags are the memory format proprietary to RED systems, most notably the RED Epic 8K, RED Raven, and RED Scarlet. With transfer speeds up to 300MB/sec, these cards are more than fast enough to capture 8K footage, though will need a RED Mini-Mag Station to pull information off of the cards.

SxS Cards

SXS Memory Example

Developed by Sony, the SxS cards work using the PCI ExpressCard slot, found on laptops and some video cameras. Despite being developed by Sony, Sony does not exclusively use the file format, though popular cameras which accept the SxS card are the ARRI Alexa, Sony FS55, and the Sony FS5. Be design, the SxS card is fast, allowing up to 1.3 Gbit/sec transfer speeds with the SxS Pro format, and with a theoretical limit of 8 Gbit/sec.

P2 Cards

Developed by Panasonic, the P2 card system was first introduced in 2004 and is still used on many Panasonic Video Cameras. Most known for its use on the Panasonic VariCam, the P2 format comes in three different styles – the P2 card, the microP2 (which shares the design of the SDXC card system), and the expressP2. While this memory system is fast (with a maximum data rate of 1.2 Gbit/s), it is exclusive to the Panasonic brand.


That, for the most part, covers it for all of the current media used as of right now. Collectively, one would hope that in the future, we’d have one or two standards that would be hot-swappable from camera system to camera system, but until then, we must learn the inner workings of a large range of memory solutions.

Author: Zach Sutton

I’m Zach and I’m the editor and a frequent writer here at I’m also a commercial beauty photographer in Los Angeles, CA, and offer educational workshops on photography and lighting all over North America.

Posted in Equipment
  • Eric Bowles

    Nikon has taken two approaches. With the D500 and others, they have a moderate sized buffer and a fast write speed that can write stills at 150 MB/s to the SD card. The balance goes in the buffer and buffer size limits burst length to about 12 seconds with SD and 20 seconds with XQD. The alternative approach is to just make small files per frame – 12 bit rather than 14 bit and reduce the size. The Nikon V1 had 30 fps and 60 fps options, but it was just for a short burst with smaller frames and no processing functionality.

  • Hank Roest

    The Olympus-claimed spec I quoted is 237 mega BITS per second (not MB/s). But Lord knows what the sustained bit rate is when it’s trying to record 20MP raw files at 60 frames per second; similar to the Nikons, I’d suppose.

  • Eric Bowles

    No camera is able to deliver a write speed of over 200 MB/s on an SD card – even UHS-II cards. The fastest write speed I’ve seen or heard of for UHS-II is around 150 MB/s in the Nikon D500 and D850. As Ed Hassell mentioned above, it’s largely a hardware issue with multiple components required to achieve fast speeds.

  • idi 01

    I found an SD card that my grandfather used back during his stint in ‘Nam. I could only retrieve about half the photos.

  • endinyal

    I’ve been able to retrieve data on long-forgotten SD and CF cards that were over ten years old with zero problems. Either way, if you really care about your data, consider more options – even cloud services like DropBox would be more reliable since they’re on redundant systems and are pretty much guaranteed to never “lose” your data.

  • Ansel Spear

    None of these cards are intended as long-term storage solutions. It is expected that images are offloaded to a more permanent device, freeing up space on the card.

  • Michael

    I vote for a mass adoption towards the CFexpress format to comfortably carry us forward for the next decade.

  • stan2000

    In the pictures alone, there are 7 other brands pictured!

  • Ed Hassell

    1) Camera manufacturers often use “antiquated” parts. The hardware actually incorporated in the camera may be capable of using a UHS-II card but that doesn’t mean it uses its full capability. There could be a variety of reasons, including actual interface, buss timings, buffer, CPU processing speed, etc.

    2) Technically, XQD is a subset of CF/Express, speed-limited and using only 2 lanes of the PCIe buss. The full implementation incorporates 8 lanes and can be much faster. IF and only IF the full hardware implementation for XQD is in place in the camera; and IF and only IF the manufacturer has not cut corners with the clocks and buffers involved with timing; and IF and only IF the proper firmware is in place, ANY CF/Express card could be used in place of XQD cards in the camera. However, effective read and write speeds within the camera would be limited to the original XQD card specification regardless of the speed ratings of the CF/Express card. (See also: #1, above.)

    3) Nikon’s three flagship cameras, the D5, the D500 and the D850, all use XQD cards. I suspect that Nikon will move heaven and earth, should it become necessary, to keep usable media available, one way or another. We have no way of knowing if that will be via firmware and CF/Express or by encouraging the manufacture of XQD.

  • Hank Roest

    Interesting. I have an Olympus EM1.2 with one UHS1 slot and one UHS2. When I bought it there were problems with some brands of UHS2 so I just use UHS1 and shoot stills. BUT, I came to this article specifically to find out which UHS2 card I should consider for C4K video which, supposedly, the Oly does at 400Mbps. The article seems to have been written 2 or 3 years ago.

  • Any guesses as to why so many UHS-II capable cameras barely scratch UHS-I speeds, even with the fastest cards?

    And how different in format are XQD and CF Express? How much of a stretch is it to expect Nikon to give us a firmware update for compatibility? Any guesses?

  • Sharon Ann Witteck Austin


  • Ryan Hill

    Great point, Hank. A good warning for people to keep in mind is that UHS-II, while great if your camera supports it, can sometimes cause speed issues in cameras that aren’t equipped for it. UHS-II achieves those high speeds by utilizing a second row of contacts for data transfer. While the cards will work in readers or cameras that can’t read both rows of contacts, only one row is actually active. That single row read/write mode is often far slower than first-generation SD cards.

  • Ryan Hill

    If archiving is your goal, you should definitely be transferring to more permanent storage like a RAID system way before a few years pass. These kinds of card are meant to be recorded on, dumped, and reused, not stored long term as a backup.

  • photoracer

    since around 2013 but Rob Galbreith’s memory card tests for specific cameras is more useful as you can see which cards fudge their specs and which actually meet them doing actual RAW image transfers. You can find that the fastest cards are often the smaller capacity ones of a given series since they contain less address lines and need less computer cycles to move data. Nothing newer than for the 5D III/1D-IV or D4/D800E DSLRs and XQD/CF/SD cards up to the same date.
    Looks like the CameraMemorySpeed site took over from Rob after he changed jobs. Tests are even the same.

  • t.h.

    I would like to know how long images will remain intact and retrievable on an SD card. I have heard that they become unreliable after a few years.

  • Heh, this isn’t sponsored by anyone. In fact, I have an entire section dedicated to mentioning brands and brand importance.

    But I’m not going to personally buy every brand available so that I can then release free, but valuable content.

  • Hank Roest

    Nothing about UHS-II? What about all the new hybrid cameras, including mine, being equipped with SD UHS-II?

  • Nyarlathotep

    Yeah, I’ll believe it when I see it with Nikon, unfortunately, it is uncommon for Nikon to add features when they update firmware. Usually they only patch bugs or tune minor concerns.

    And as you pointed out, as is often the case, implementing the bare necessity of hardware and sometimes using secondary systems that are a generation or two behind state of the art. So it is possibly the PCI bus is compromised such they can’t make a firmware change to accomodate. I hope that is not the case, I have a D500 that could benefit and I may replace my 800 with an 850 in the next year or so.

  • Gareth

    If CFExpress requires a firmware update for any existing camera to use it, and no manufacturers have even announced they will produce such an update – maybe its not yet time to recommend buying a CFExpress card at this point?

  • David Wallis

    sponsored by Sandisk 🙂 – other brands are also available 🙂

  • Greybeard

    A helpful overview but specifically on SD cards:
    – It might be helpful to point out that the main difference between SDHC and SDXC is the capacity and not the speed.
    – What evidence do you have that “the SDXC format, which allows for much faster transfer speeds”?
    – There isn’t much difference in claimed maximum speed between the fastest available micro SD and full size cards
    – It is true that one of the most important topics is speed but you don’t make it clear that most of the speeds you discuss for SD cards are read speeds and in camera the write speed is more important.

  • Ed Hassell

    Camera manufacturers being notoriously cost-conscious, it’s quite possible that they cut hardware corners when implementing the in-camera XQD PCIe buss. If so, firmware can’t help; iff they fully implemented the 2-lane PCIe buss, then a firmware update should allow CF/Express cards to work just fine (at XQD speeds) — if they choose to make one available. I’m hoping; as, I own two current XQD cameras: a pair of D500 bodies. And, I now have a D850 on order. Luckily, I purchased a couple dozen of the Lexar 64GB and 128GB cards just before the ax fell. I’m hoping that holds me for a while.

  • Nyarlathotep

    Thom Hogan has a little color on this subject in his latest commentary. He interviewed Nikon and Lexar/Longsys representatives during NAB. Sounds like Longsys has started to produce XQD under the Lexar name, with availability probably in June. Seems the delay was related to getting licensing squared away with Sony since Sony owns the IP. Hopefully this helps with pricing on XQD cards.

    With regards to backwards compatibility of CFExpress in XQD devices, a firmware update is a possibility. However, NikonUSA representatives at NAB did not know, or were unable to detail what Tokyo plans for support. They did say they would inquire and follow-up, but Nikon may remain silent given their historical tendencies.

  • Good advice, I added that, thanks.

  • Turniphead

    Exactly, which is the clue as to the origins of the “arbitrary” number; it was chosen by Lexar as it represented the 1x CD-ROM read speed – i.e. 150KiB/s. So all their cards are measured in comparison to basic CD-ROM performance, which makes sense as it was the predominant portable writable media standard back in the day. Of course now it’s somewhat of an anachronism 😉

  • Ilya Zakharevich


    “dividing that number by 6.666” would, probably, be better rewritten as “multiplying by 0.15”.

  • Scott Kirkpatrick

    I see SDXC cards everywhere (have drawers full), and I do video in addition to stills with mirrorless cameras. I see that Black Magic has an HDMI-driven recorder that will use SDXC cards. Is that a coming thing? More generally, which of these cards is fast enough for use in Sony or Panasonic current video-enabled still cameras? (I’m actually using Leica SL, have you had any rental experience with those?) And what is the impact of the splitting of files into 4GB chunks when recording to a FAT-formatted card? How many frames are lost, if any? At 4K rates in-camera, that’s only 5-6 minutes.

  • DrJon

    Since most cameras top out at a speed well below what some of the faster cards can manage I find speeds measured in a camera to be the most useful, although a faster card can help with download speeds when in a card reader. How fast to go (above the camera limit) depends how much that reduced reading time is worth it (probably quite a bit for pro sports shooters, less so for others).
    I find this site the most useful:

  • Ed Hassell

    Yes, CF/expres is the (probable, but not certain) wave of the future. However, XQD has many problems: Micron sold Lexar to the Chinese who have yet to begin manufacturing of the “Lexar” brand XQD. Sony is the ONLY current manufacturer of XQD cards and they have just raised prices dramatically, citing memory costs. CF/express is indeed the “future” of XQD; however, backward compatibility is NOT guaranteed (and, currently, not possible). While the PCIe buss is indeed the same, timings are not necessarily the same and hardware implementation in existing cameras may or may not allow for required firmware upgrades to allow CF/express to be used in XQD cameras. You need to contact the camera manufacturer for their take on individual camera models as to what their future card use entails. Good luck.

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