SDXC cards - confusion over UHS speed ratings

[wlaidlaw]

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I was looking at what SDXC cards to order for the SL. I know that slot 1 takes cards up to UHS-III rating and writes at up to 100mB/s, whereas slot 2 takes cards of UHS-I and above rating but only writes at a maximum of 30 mB/s. When I looked at Amazon, I did not progress very much. There were Transcend cards called UHS Speed Class 3 (U3) but when you look at the detailed spec it says it is only UHS-I with a write speed of 95 mB/s. There were other cards from Lexar which said they were UHS-II but had write speeds of 150 mB/s (U3). There did not appear to be any cards listed as UHS-III, which seems to be a different thing from UHS-I but speed class U3. Confused - I certainly am. 

 

Wilson

[ramarren]

I'm just going to stick my Sandisk Extreme Pro SDXC 64G cards into it and see how it works.... :-)

[wlaidlaw]

After wading through the SD association standards (better than Zolpiden for insomnia), I think I now understand it and Leica appears to have made an error in their literature. UHS-I and UHS-II refer to the bus interface standard/generation/speed, which can then be further split into various SDR speed levels. There is as far as I can see, no UHS-III standard at present. Then for SDXC, there is the speed rating for which at present, there are only two standards 1 and 3, shown as 1 or 3 with a "U" drawn round them. Finally there is the manufacturer's maximum burst speed rating usually given in either MB/sec or confusingly as say 1,000x (times what is not stated). So it looks as if for slot 1 we need to buy a UHS-II card with a speed rating of U3. For Slot 2 a UHS-I will do with a speed rating of U1 or U3. Anyone still awake out there? 

 

I show three examples of cards below for Slot 1. The SanDisk having a much higher (and inaccessible on the SL) potential write speed is over four times the price of the Lexar and nearly double the price of the Transcend.

 

Wilson

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[wlaidlaw]

Just out of interest, these cards above are 1000 times the size of the first 64MB MMC memory card, I bought for my Leica Digilux Zoom in 1999. It cost me from memory around £125. The Lexar card above is £25. So 1000 times the size and a fifth of the price. This is impressive progress. 

 

Wilson

[Echo63]

confusingly as say 1,000x (times what is not stated). 

times a CD burn speed.

 

remember how CD burners used to be "2x" then "4x" and seemed to top out around "32x" 

1x is 153.6 Kilobits per second.

so your "1000x" card should transfer data at 153600 kbps or 19.2 megabytes per second (which sounds faster ?)

[pico]

I was looking at what SDXC cards to order for the SL. I know that slot 1 takes cards up to UHS-III rating and writes at up to 100mB/s, whereas slot 2 takes cards of UHS-I and above rating but only writes at a maximum of 30 mB/s. When I looked at Amazon, I did not progress very much. There were Transcend cards called UHS Speed Class 3 (U3) but when you look at the detailed spec it says it is only UHS-I with a write speed of 95 mB/s. There were other cards from Lexar which said they were UHS-II but had write speeds of 150 mB/s (U3). There did not appear to be any cards listed as UHS-III, which seems to be a different thing from UHS-I but speed class U3. Confused - I certainly am. 

 

All SD*C cards are not equal because they are made of different materials and by different methods. But there are minimum standards.

 

When looking at speed classes please know that the SD Association gives minimum speed of the card for video applications. SDHC and SDXC are, of course the fastest and are a simpler choice but not necessarily better for still photography. It depends upon hardware and firmware, too.  SDHC cards should work in SDXC devices, however the full potential of SDXC may not be implemented. They are really different standards or protocols. Does the SL support SDXC? (and why, if it is true, do they have two differently rated slots?)

 

To me, only the Minimum Serial Data Writing Speed is important. SDHC has two,  UI @ 10Mb/s and U3 @ 30Mb/s. That's what you can count on, minimum. What is sometimes advertised is the bus speed of the card. For UI it is either 50Mb/s or 104Mb/s (SDHC,SDXC, respectively) and for UII it is 156Mb/s or 312Mb/s. Those are theoretical maximum speeds - rarely achieved.

 

The SD Association does not give the maximum speed of a card. That's up to the manufacturer to declare, for better or worse, but it should not be above the Speed Class or SDHC Speed Class.

[pico]

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Just out of interest, these cards above are 1000 times the size of the first 64MB MMC memory card, I bought for my Leica Digilux Zoom in 1999. It cost me from memory around £125. The Lexar card above is £25. So 1000 times the size and a fifth of the price. This is impressive progress. 

 

Wilson

 

Scale of manufacturing and statistical QC make a difference, eh?   In 1988 I bought a Mac and wanted to hack up memory which was $999.00 a MB! Today? Amazing.

[digitalfx]

I was hoping (and assumed) they were going to support the new UHS-II cards:

https://www.sandisk.com/home/memory-cards/sd-cards/extremepro-sd-uhs-ii

 

If you look at the back it has an additional set of contacts.

 

Fuji was the first camera to add support for these last year....hopefully Leica has included support for these cards as they make a huge difference.

 

 

EDIT:

Looking at the Leica website it says UHS-II:

SD 1 slot (UHS II)

 

This is great news!!! This card actually supports writes significantly faster than 100MB/s, so hopefully this is not a bus speed limitation by Leica as the card is much faster than what Leica claims in the specs. 

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[pico]

SDXC allows four writes simultaneously but that seems only to help in offloading data. Correct me if I am wrong.

[digitalfx]

SDXC allows four writes simultaneously but that seems only to help in offloading data. Correct me if I am wrong.

 

The card I linked is at least 50% faster writing buffer data to the card.

[psss]

I don't understand why Leica takes a step forward in providing 2 slots and then takes one back by putting a slower one? makes no sense at all....

[digitalfx]

Hey, at least we finally get a modern SD card...Leica has been putting previous generation card slots in every camera. Very frustrating considering the premium we pay. The UHS-II card was an option when the Leica T was developed...which they obviously didn't choose. Fuji has been using it on their latest cameras since last year, no excuse for Leica to use old tech on a premium brand.

[ramarren]

Hmm. 

 

Well, I suppose if you're going to push the movie capture capabilities or fire off max speed sequence bursts and need to optimize the camera for those uses, the latest round of highest speed cards and high speed slots make sense.

 

For me, however, the "old" 95mbps cards are going to be perfectly adequate for a while yet. I'm mostly a one-shot-at-a-time shooter. :-)

[ski542002]

Hello: So, Sony just announced the Superfast Sony SF-G Series SD, UHS-II SD memory cards, the “world’s fastest” SD card according to Sony, with an impressively fast write speed up to 299 MB/s and a read speed up to 300 MB/s.

 

I'm wondering if the SL can take advantage of this speed in slot 1, or would it be a waste of money?

[ramarren]

Hello: So, Sony just announced the Superfast Sony SF-G Series SD, UHS-II SD memory cards, the “world’s fastest” SD card according to Sony, with an impressively fast write speed up to 299 MB/s and a read speed up to 300 MB/s.

 

I'm wondering if the SL can take advantage of this speed in slot 1, or would it be a waste of money?

 

 

Likely a waste of money. I did some testing back at the end of 2015 with the SL and found it could only write to the card at about 25% of the speed that my Lexar 128G cards could achieve with the card reader in my Mac mini. There's really no point to paying more for faster speeds. (I posted a bunch of test results on some thread here about that time... )

[leica1215]

Yes, I have had 300MB sandisk, even though I haven't run any test, but my feelings is just about the same with my newly purchased sandisk 95MB one, maybe my old 95mb one is counterfeit one, back then I did felt 300 one are a bit faster

 

 

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[scott kirkpatrick]

Testing these fancy new cards on a camera is not going to show what they can do, as the cameras are designed within bandwidth and battery power limitations.  To see maximum delivered bandwidth, I would test by reading and writing files with a latest generation card reader and USB3 port (unless there is an Apple connection faster than USB3).  Maximum device bandwidth is probably seen in external video recorders that capture onto SD cards, since that is all they have to do.

 

There is an interesting arms race in progress in multi-card support.  Leica, being rather conservative, is not the leader.  The SL can only stream one form of output per picture to storage, while others can put raw files on card 1 and jpegs on card 2.  Most of the 2016 products have only one UH(II) socket, with the second card only having UH(I) contacts.  But I think the Olympus OM-D E-M1.2 went to supporting the faster bus on both cards.  Don't know what the X1D and Fuji medium format cameras support.  As a result of having only one card with a fast bus, video is generally limited to recording on card #1.

 

scott

[caissa]

As stated before video is much more demanding than photography. So the fast cards are mainly interesting for video users.

And the *official standards" (UHS-II) only guarantee about 30 MB/s write speed at the minimum. (for 4k video)

Any other speed numbers are only "inventions" of the sellers.

 

For photography with the SL "burst mode" is the maximum you can get. This means filling the 2 GB buffer with 11 frames per second. After about 3-4 seconds it is full.

Users have measured how long it takes to empty the buffer. The typical write speeds found with SL were in the range of 30 MB/s .

If 90MB/s cards gave the average time, then the "fast" cards were faster - by about 5 seconds.

That means the fast cards were 5-10% faster.

 

It is up to you to decide if the 5 seconds are worth the higher price.

 

What about writing in parallel to the 2 slots ?

AFAIK the camera writes sequentially. So for better speed, better use only one slot (especially for video) - slot 1 is UHS-II.

If using both slots (with 2 copies) then the slower slot will be the limiting factor.

Will it be faster with only one slot ? Yes, probably, by the 5-10% (see above).

 

In normal use for photography (not burst mode), you will not notice a difference, as the 2GB buffer will keep everything smoothly going. You can continue shooting until the buffer is full.

If you often fill the buffer the 5 seconds gained can be valuable. If you never fill it, you will never see the speed up. Depends on your way of shooting.