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Since there are fake SD cards available in eBay, I think it worthwhile being able to check that your SD card performs reasonably.

I've found a free performance utility on the German c't electronics magazine website. The program is very small, simple to use and has an option to show English language. It's H2TESTW.

H2testw, Download bei heise

One use is to completely fill and read back a SD card to verify both its capacity and its data integrity.

The use I want to look at here is its measurement of read & write speed.

The SD Class speed rating is good for DSLR usage because it specifies the minimum sustained write speed in MB/s. It's easy to interpret.

Class 2, 4, 6, 10 = a minimum sustained writing speed of 2, 4, 6, 10 MB/s.

Just to make things more interesting, SD speed in the specification document is measured with a MB of 10^6 (1,000,000), while the capacity is measured with a MB of 2^20 (1,048,576). See the bottom of page 6 in http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf

Older SD cards are more difficult to interpret. They use a "x" rating e.g. 60x which is compared to the CD standard speed of 150 KB/s. So 60x is 9 MB/s. The confusing thing is that this can be either the read or write speed, and since the reading speed is usually faster than the writing speed, some manufacturers measure that. So being able to actually determine the true writing speed of an old SD card yourself is a good thing.

Here is the measured speed in MB/s of the SD cards I've got here (1000 MB test file):

Labelling	Write Speed	Read Speed	Comments
Kingston 2 GB "0715" (YYweek)	6	13.6	Both Kingston cards look the same. Used in a Zoom H4 digital audio recorder
Kingston 2 GB "0947"	8.9	15.2	Used in a Samsung P&S camera
Apacer 2 GB "60x"	3.7	8.8	Used in K100DS
Apacer 8 GB Class 6	8.4	15.9	Two owned - same speed. K20D spare cards
Transcend 8GB Class 10 "20MB/s"	16.2	20.3	K20D main card

Notes:

The "60x" rating on the label is justified for the Apacer 2 GB card if you use 10^6 Megabytes: 9 MB/s. However, using the modern Class rating, this is only a Class 2 card. (There's no Class 3.)

The Apacer & Transcend 8 GB cards easily meet their class rating.

The max. reading speed of the Transcend (20.8 MB/s in 10^6 Megabytes) in my cheap A-power All-in-1 mini card reader seems like it's close to top reading speed for a USB 2 card reader. Compare the results to those measured in this translated 19 SDHC card roundup at the German Hardware-Infos website where the following 3 card readers were used:

• SanDisk ImageMate All-in-One
• Sapphire Card-Reader/Writer Sapphire Card-Reader/Writer
• takeMS 64in1 Card-Reader/Writer takeMS 64in1 Card-Reader/Writer

Google Translate of SDHC roundup

The highest reading speed measured was 21,895 KB/s. If that's 2^10 Kilobytes, that's 22.4 MB/s in 10^6 Megabytes.

The question is often asked "Should I buy an expensive SD card?" I'm not into DSLR video and I don't buy top brand SD cards. If video in a DSLR is important to you than the answer may well be "Yes". However, even the Transcend Class 10 card was not expensive when I bought it off eBay from a vendor in the Isle of Man. I've never had either a electronic or mechanical failure for with a SD card, so the advice of only buying top brand-name SD cards may well be a waste of money for non-video usage.

"Should I use a Class 10 card in my camera for non-video usage?" I pull the SD card out of the camera and transfer the files via an external card reader. Doing this, the Class 10 card tested here produces a 27% faster transfer (reading) rate than the class 6 card which is obviously a good thing.


Dan.

[gmturner]

very interesting. Thankyou for putting in the time and effort.

I wonder how the k-7 would fare and if a 30mb/s card would make a difference. Ive been thinking of getting a 30mb/s card for my k-7 to increase burst longevity but this makes me think twice.

Also will be farely important for the k-5 when i get my hands on one seeing its buffer will fill quicker.

[ChrisJ]

Just to bring this thread up to date, there are now UHS (Ultra High Speed) SD cards trickling onto the market such as this one (from a reliable supplier - usual disclaimer, just a satisfied customer over many transactions)

Sandisk Extreme Pro SD HC UHS-1 8GB Card 45MB/s 300x | eBay

You'll notice that the speed Class is back at 1, but this is UHS Class 1 (the first in this development) and has a speed of at least 45Mb/s which is 50% faster than a Class 10 card.

Unfortunately on a Pentax you won't see much difference as the internal processor is not as fast as the card so you'll still get the 5 minute limitation on HD video and the limit on the number of frames in burst shooting mode and the frames per second, though this has raised slightly on my K5.

The real difference is in the download speed, but there's a fly in the ointment here too as you need a USB3 card reader and a computer with USB3 ports to get the maximum speed. (USB3 is capable of transferring data at up to (notice the 'up to') 5GB per second!) But with these in place I can download a full 8Gb card in under 3 minutes.

Chris

[dosdan]

The real difference is in the download speed, but there's a fly in the ointment here too as you need a USB3 card reader and a computer with USB3 ports to get the maximum speed. (USB3 is capable of transferring data at up to (notice the 'up to') 5GB per second!) But with these in place I can download a full 8Gb card in under 3 minutes.

Thanks for the news, Chris. Can you please try h2testw to determine W & R speeds.

I've now got a slightly faster USB2 reader. The Transcend Class 10 on 7000MB test data measures:
Write: 17.1 MB/s (6m 49s)
Read: 21.4 MB/s (5m 26s)

At that speed, reading a full 8000MB would take 6m 12s.

Dan.

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Last edited by dosdan; 10-15-2011 at 08:42 PM.

[dosdan]

Measurements for the Patriot LX 32 GB Class 10 card (6000MB test file):

Write: 11.6 MB/s
Read: 19.5 MB/s

The write speed is not far from the minimum expected for Class 10 performance so it may not be the best choice for sports or video use. General photography should be fine.

Dan.

[Docrwm]

Since this thread started with how to check for fakes I thought this information might add to the discussion. On the counterfeit cards I have unfortunately run across the easiest way to tell was by looking at the real storage space they had available. All of the ones that turned out to be fakes had some cosmetic difference, that was sometimes tough to call if you weren't intimately familiar with that brand, but they also cheated on the size - 8mb really had <2mb, etc.

[Chex]

I just tested my card with these results with H2testw.exe standard USB 2.0 port multi-card reader (it's a 52-in-1 internal 3-1/2" drive bay reader).

Silicon Power SDHC - 16GB Class 10
Writing speed: 14.0 MByte/s
Reading speed: 18.6 MByte/s

I would assume that my 8GB Class 10 Silicon Power SDHC card would perform the same or very close.
Sure would like to try a USB 3.0 reader to see if there's a difference!

[Docrwm]

I just tested my card with these results with H2testw.exe standard USB 2.0 port multi-card reader (it's a 52-in-1 internal 3-1/2" drive bay reader).

Silicon Power SDHC - 16GB Class 10
Writing speed: 14.0 MByte/s
Reading speed: 18.6 MByte/s

I would assume that my 8GB Class 10 Silicon Power SDHC card would perform the same or very close.
Sure would like to try a USB 3.0 reader to see if there's a difference!

Some of the older reviews (2009ish) found significant differences in cards of the same class from the same manufacturer but of different sizes.

[Chex]

hmm thanks, I'll throw it in and test it later.. not sure what real world difference it will make for my shooting lately... time lapse generally needs size over speed!

[dosdan]

Measurements for the Kingston 32 GB ultimateX 100x Class 10 card (30,000MB test file):

Write: 14.1 MB/s as purchased (15.1 MBs after "formatting" in the K-5.)
Read: 21.1 MB/s

Dan.

[bdparker]

I thought I'd do some checking myself because I believe that there might be other factors that may play against the outcome.
I have 3 16Gb card of various ages and quality as listed below.

SanDisk - SDHC Ultra Class 4 - 16Gb
Writing speed: 10.8 MByte/s
Reading speed: 16.7 MByte/s

Team - SDHC Class 10 - 16Gb
Writing speed: 14.4 MByte/s
Reading speed: 16.7 MByte/s

SanDisk - SDHC-I Extreme Pro Class 10-U1 - 16Gb
Writing speed: 14.8 MByte/s
Reading speed: 16.8 MByte/s

The last SanDisk Card boost a speed of up to 95MB/s in this new 'U' type class, which I don't see in any of these figures, mind you I am not using a external SD/USB reader, all three are through the Laptops internal reader. Therefore, for what I can see, these three card are suppose to be different but all have similar figures, This come down to the read/write speed of the Laptop for this test, which doesn't worry me much, because I don't necessarily care how long it takes to upload.

But I can tell you there is a slight difference when used in the camera (do a rapid fire series of shoots and roughly see how long it takes to internal process - first to last)

[Chaos_Realm]

I did this a little while ago and got some interesting results, Although this was more directed at the difference between USB 2 and USB 3, for downloading the days photos.

https://www.pentaxforums.com/forums/digital-processing-software-printing/1508...eed-tests.html

[Operator]

Posted this in the K-5 section, when I guess it would have been better to post it here. Here it is nonetheless.

Well I got all my cards in. Using ChkFlsh on my 2009 Toshiba (Vista) laptop here are my results if anyone cares. I plan to use 2 for my K-5 and 2 for my GoPro Hero3 Black Edition.

All WRITE SPEEDS.

Micro Samsung 16GB Plus Extreme Class-10
15.85 mb/s

Micro Sandisk 16GB Ultra UHS-1
11.45mb/s

Samsung Essential 16GB Class-10
16 mb/s

Sandisk Extreme UHS-1
17.68 mb/s

Sandisk 2GB Class-2
6.36 mb/s

Kingston 4GB Class-4
4.5 mb/s

32 GB Film Pro Class-10
10.5 mb/s

Micro 2 GB Samsung
6.8 mb/s

32 GB Adata Class-10
4 mb/s RETURNED

I presume my laptop is what is holding back some of the numbers I received.

[bdparker]

Windows Vista is part of the problem, that why Windows 7 came out so quickly, to fix the read/write issues with external drives ,USB devices and card readers.

[dosdan]

3 Sandisk SD cards ( card speed MBytes/s measured in h2testw in a USB3 ext card reader)

Card	Write	Read
Ultra 16GB	9.04	43.4
Ultra 32GB	10.6	43.6
Extreme Pro 64GB	81.3	83.8

I'm using the Extreme Pro 64GB in a K-3, which supports UHS-I. If I use an Ultra in this camera, it is noticeably slower.


Dan.