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.

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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