Class 10 vs UHS-1

Started Jun 15, 2012 | Discussions thread
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Jim Holloman Regular Member • Posts: 140
Class 10 vs UHS-1

The following is an exchange with SanDisk regarding UHS SD cards. Reach your own conclusion.

I purchased this SanDisk UHS-1 SC Card for use in the OM-D:

I have received the card, and there no mention of "UHS" on the label nor on the package. Nor, does it have a 'U' letter with a '1' inside of it as you find on Transcend SD cards (number contained within a U-shape). It does have a simple 'I' on the label, but by itself such a mark has no significance.

So, I sent a message to Sanddisk. This is part of the reply:

"Please be informed that UHS-1 (Ultra high speed) is equivalent to class 10. All UHS-1 memory cards have 10MB/s of minimum data transfer speed same as a class 10 card. There is no difference in the data transfer speeds of these memory cards and also they are identical in their technical specifications as well. All SDHC and SDXC class 10 memory cards that we are manufacturing are UHS-1 also."

The last statement may be valid. I question the other assertions.

This is from: with emphasis added.

"UHS Speed Class

Cards that comply with UHS show UHS-I or UHS-II ==> on the label


"UHS-II cards, to be defined in Version 4.0, further raise the data transfer rate to a theoretical maximum of 312 MB/s"

This is from:

"...UHS-I is the fastest category of card available today with a bus interface speed of up to 104 MB/s, while UHS-II is expected to reach 300 MB/s..."

This is from:

"Beyond Class 10 is the UHS Speed Class. UHS stands for ultra high speed and includes cards that have speeds up to 312 Mb/s. The UHS speed class logo includes a number contained within a U-shape. Currently, there is only one UHS speed class: UHS Speed Class 1, which is designed for the UHS bus interface. Cards in this class will usually be noted as SDHC UHS-I or SDXC UHS-I."

This is from:

"The new Class 10 SDHC UHS-I cards boast a staggering four times faster transfer rate compared to Class 10 alone, realizing transfer speeds of up to 85MB/s when paired with advanced UHS-I compatible devices."

-- hide signature --

UHS-II cards will clearly not be the same as Class 10 cards. So, to avoid such confusion, please consider labeling all of your UHS cards as either UHS-1 or UHS-II cards.

The Sandisk SD card that I purchased is a Class 10. It shows a maximum transfer of 30 MB/s (for reading only, write speed slower) -- not 85MB/s.

Thus, the information you give me is inconsistent with the information I find on various sources on the Internet.

This information is to be posted at:

In a message titled "Class 10 vs UHS". Please feel free to respond to the message.

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