What Is a UHS-II SD Card and Why Would You Want One?

What Is a UHS-II SD Card and Why Would You Want One?

Back in the day (not all that long ago, in fact), the only memory cards you would find in a “pro”-level camera were Compact Flash. That all changed as SD cards started to get faster and faster. Speeds up to 95 MB/s were great for emptying out the buffer on machine-gun mode and writing 1080p footage, which meant that space in the bodies could be used for other things. These cards were great. You could dump 64 GB of images while you watched the evening news. Then came along UHS-II cards, and if you’re not using them yet, you should definitely add them to you list next time you're upgrading cards.

It occurred to me a while back that the slowest link in my data chain was my memory cards. First world problems, I know. At the average of 87.5 MB/s read rate I was getting with my UHS-II cards, a 32 GB shoot would take around 6-7 minutes to copy over to my drive. Now, this is really not that long; I could live with it for sure. However, sometimes I’m shooting full days with multiple shooters, and if we are dumping cards at the end of the day, this could mean 30-40 minutes of card copying between us. That time could be better spent at home with our families. Enter UHS-II.

The Technical Jargon

Before we dive into this, let’s take a look at the standards for SD cards. Specifically, let’s take a look at UHS as this is what we’re worried about for read and write speeds. UHS stands for Ultra High Speed and is a bus standard set out for use with the SD card standard. Simply put, it is a standard method for reading and writing data to SD media. UHS-I enabled cards of up to 104 MB/s with an increase in clock speed and the UHS-II standard increased this by adding a second row of contacts to the card. This is the key. Not only have the cards themselves become faster, but we now have two sets of contacts to transfer data. Using these in half-duplex mode (both sets used simultaneously for reading), the cards are able to transfer a lot of data extremely quickly. But that’s not what we’re here for, so head over to the SD Association for more technical details.

This image has very little to do with the topic at hand, other than the fact that I was able to copy it really quickly.

So, How Much Faster Are They?

As you may have guessed from my header image, UHS-II cards are quite a bit faster than UHS-I cards. In my experience, with a good quality UHS-II card reader, UHS-II cards are not only significantly faster, but have a much more stable sustained transfer rate. With my 280 MB/s rated SanDisk Extreme Pro cards, I average 245 MB/s transfer rate, for images, with my current setup. That takes my 32 GB transfer down to just over 2 minutes. That end of day dump now only takes 10-15 minutes for all our cards and we can get home sooner. Of course, your camera needs to support UHS-II cards, and you’ll need USB 3 and a UHS-II card reader to get all of this working, but for a volume shooter, this can be a huge time saver.

For 4K Shooters

The other thing that these cards feature is a faster write speed. With the new UHS Speed Class 3, SD cards can write at 30 MB/s as well. This is great news for video shooters as 4K footage can be recorded smoothly with no dropped frames at frame-rates of up to 120fps.

In Conclusion

Right now, UHS-II cards are typically around three times the cost of their UHS-II counterparts. However, if you can justify the purchase, the speed increase is worth it when transferring large amounts of data. Although the UHS-III standard has been defined and finalized (624 MB/s theoretical), it has still yet to make its way into commercially available cards and will likely be extremely expensive when it does. For now, UHS-II cards are a great deal for those needing more speed. Head over to B&H to check out the options available for you.

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16 Comments

Sebastian Erras's picture

You should mention that your camera should be UHS-II compatible, too. Otherwise you won't be able to fully make use of the increased write speeds during a shoot.

and use a UHS-II card reader.

Ryan Mense's picture

"Of course, your camera needs to support UHS-II cards, and you’ll need USB 3 and a UHS-II card reader to get all of this working, but for a volume shooter, this can be a huge time saver." It does say these things.

Ariel Martini's picture

But it doesn't say that 90% of the cameras out there don't support it.

Rob Mynard's picture

The problem here is that it's not just does your camera support UHS-II cards, as most cameras can use UHS-II cards even though they have UHS-I card slots. However, using a UHS-II card in a UHS-I camera can result in slower write speeds than using the correct cards. For example in the Nikon D750 the Lexar UHS-II 300mb cards will only write at 70mb/s as opposed to the 95mb/s of the UHS-I

Ryan Mense's picture

Still has nothing to do with my original reply.

Ariel Martini's picture

Also, if your camera is not UHS-II compatible, those cards will perform SLOWER than UHS-I card. So in this case don't make the switch (yet)

Aaron Bratkovics's picture

"each card was taking about 3.5 minutes to import into Capture One Pro. That doesn’t seem like a long time unless you have 25 crew and clients standing around anxiously waiting to see the latest images. "

haha. God forbid they wait 3.5 minutes.

I have a 128GB UHS II card in my Nikon D500, but it pales in write speed & data transfer speed to the 128GB XQD card I also have installed in there. It is the first time I have ever been able to just hook a USB3 cable between my PC & camera and have the shots download in seconds rather than minutes. Amazing

Spy Black's picture

That's because the UHS II slot in your D500 is not full speed UHS II, it is half-speed. Don't ask me why, but it is a serious shortcoming in the camera's design. Furthermore, if you have both card types in your camera and are writing to both, your camera will only write as fast as the slowest bus, which negates the advantage of XQD. So if you want the full speed of your XQD card, leave the SD slot empty.

Jonathan Krier's picture

Just a heads up, I got the Lexar 1000x UHS-II and it can't record 4K on the 5D IV, shuts it down after a couple seconds. Hesitant to purchase another SD card for it, but CF is inconvenient when the Macs have an SD slot.

Anyone else have this problem, or can you confirm a certain SD card works in the 5D IV?

There appear to be a couple of errors in the article. The term "UHS-II" is used in place of UHS-I when comparing the old vs new.

Spy Black's picture

One other item to note is that not all UHS II card buses in some cameras are full speed UHS II. Why this is I'm not sure, but the D500 is one example of this, it's only half speed. I'm not sure if the A9 suffers the same fate, however, if you write to two cards at once, your write speed will only be as fast as your slowest bus, which on the A9 is UHS I. Why manufacturers are doing this is beyond me. Also many new cameras still use USB 2, when USB 3 has been around for quite a while now. There is apparently some production cost savings in doing this, but it strikes me as foolish penny-pinching.