SDHC card Help!! THANKS!

[RunOrDie]

Hey everyone, Ok, so I have the Sandisk Extreme Class 10 16GB SDHC. In order for the card to reach it's full potential, do I need a good card reader as well? I am using my built in Lenovo card reader and all I'm getting is an average write speed of 20MB/s. I am not getting anythin...g higher. Even my Class 6 Lexar Platinum Ii is reaching the 20MB/s mark.

Another question that is totally unrelated, but can we clean the surface of Nikon D7000 camera bodies? If so, with what can I clean with? Is it just me or is the D7000 body really sticky? Is it b/c of the magnesium alloy body?

Oh ya, one more question I forgot to mention. As I am still shooting Jpeg, the SDHC performance is all very similar right? Between UHS-I or Class 10 or even Class 6? The only big notice I found was when I was shooting Raw...

So mostly all SD cards perform similar when shooting 1 Jpeg that is roughly 3MB in size right? So I guess there is not real need for my to buy the UHS-I SD... Any help? Thanks again

THANKS SO MUCH!

[alphavalues]

These might explain the xfer speeds you're seeing:

USB Transfer Rates
SDHC speeds
PCIe architecture

[RunOrDie]

Hey, thanks for your reply to my SDHC thread. BTW, I read the LONG thread, I also posted their but with no reply yet

Do you know why my Lexar Class 6 is performing the same as my Sandisk Extreme Class 10? Is it b/c of my laptop card reader? If so, do I need to upgrade?

So an UHS SD won't make a difference when copying pictures, since my built-in card reader is slow? If so, how can I check my max read/write speed for my card reader?

Are all SDs made the same? Like would 1 Sandisk Extreme Class 10 perform betetr than another of the same?

Also, when I shot 10 continuous RAW pictures, it took 13sec for the Sandisk Extreme and 23sec for my Lexar. For JPEG, they both took roughly 12sec for all of them to appear on my playback on the D7000.

I am really new to this stuff...THANKS SO MUCH!

[alphavalues]

The bottleneck is your harddrive. They've gotten orders of magnitude faster in the last few years, but reading and writing magnetic bits on a spinning platter will always be dog slow. Try googling for info on SATA read/write speeds for some data about the difference between protocol speed, bus speed, and real world read/write speeds.

I've got a Lenovo R500 with a builtin SDHC reader. I'm using a Seagate Momentus 7200, which is not a shabby disk at all and 'hdparm -t' shows buffered disk reads on a live, mounted filesystem (ext3) at around 100MB/s, give or take a few megs. My understanding is that Windows non-server editions don't enable all the SATA features, so they tend to run significantly slower. Plus, when you're reading from the card and writing to the disk, both operations are fighting for limited I/O across the CPU (google IRQ for details).

I consistently get 30-35MB/s off my Class10 32GB cards, but I can see my write buffers fill up every few seconds, and they force the reads to stall while the buffers flush. My feeling is that your speeds from SDHC to SATA are normal for Windows non-server OS's, but I have no persoal experience to verify that. Again, google is probably your friend. I'm happy with the speeds I'm getting, as my RAW files are about 20MB each - so it works out to about 1.5 files/sec. If I've shot a few hundred images, it takes a while, but it's nothing I'm worried about. At work, we measure our datasets in TBs, and read/write to RAID arrays the size of small cars, so I have no complaints about what my little laptop can do for me.

On Windows server editions, you can use 'perfmon' to examine I/O across any system devices with a fair amount of granularity. You might try looking for it on your system, or googling around for whatever the equivalent tool is called on your system.

As for the difference in RAW retrieval b/w your Sandisk and Lexar, I have no idea. The RAW format includes an embedded jpeg preview, that's what your camera (and digikam, for example) use to preview RAW pictures. Given a proper test with controlled variables that make sure the camera is perfomring identical math for each shot written to either card, I wouldn't expect to see too much difference - the bottleneck is the cubic interpolator that's creating the jpeg preview, not necessarily the bandwidth to the card. At top speed (which will never happen in the real world), a 20MB RAW file will take 3.3 seconds to write to a Class6 card, while the same file will take 2 seconds to write to a Class10 - assuming they're formatted identically, etc.

[RunOrDie]

THANKS FOR THE DETAILED ANSWER. So to conclude, I do need a good Card Reader for my laptop or computer? I am not achieving speeds above 20MB/S from either cards, which I think the Class 10 Extreme would at least be around 24MB/S....

Also, is all SDHC cards made differently? Like would an Sandisk Extreme Class 10 perform the same as another Sandisk Extreme Class 10?

Thanks again!

[alphavalues]

To conclude, any decent card reader (like the one builtin to your Lenovo) will show the same xfer speeds you're seeing now until you find a way to unbound disk I/O.

As to your second question, manufacturers should be using quality control procedures to make sure every item they ship performs to spec. I've never had a problem with SanDisk cards, I believe most people think they are among the more reputable manufacturers. But that doesn't mean it isn't possible you have a dud. Try comparing them in different devices/readers to see if the one needs to be replaced.

[JFSanders]

The faster cards mean better write performance in your camera hence the faster speeds when shooting bursts. It won't make a bit of difference when you download to the computer as has been said. Until the motherboards catch up with bus speeds and 64 bit software.

Jim

[RunOrDie]

OH, so a faster card only matters when shooting bursts, right? If I shoot like only 1 JPEG picture, it doesn't matter then?

So, basically, when is it necessary to use an UHS class?

Also, when I shot 10 continuous RAW pictures, it took 13sec for the Sandisk Extreme and 23sec for my Lexar. For JPEG, they both took roughly 12sec for all of them to appear on my playback on the D7000....why is that?

[JFSanders]

Originally Posted by RunOrDie

OH, so a faster card only matters when shooting bursts, right? If I shoot like only 1 JPEG picture, it doesn't matter then?

So, basically, when is it necessary to use an UHS class?

Also, when I shot 10 continuous RAW pictures, it took 13sec for the Sandisk Extreme and 23sec for my Lexar. For JPEG, they both took roughly 12sec for all of them to appear on my playback on the D7000....why is that?

It is to your benefit to use the UHS card when you know that you are going to be shooting at a very fast pace or when you are shooting in RAW format as the camera will be able to keep up with you. It will do this because the buffer on the camera will not fill up as fast as it would with a slower card.

The reason that the jpegs are closer in performance is due to the fact that the camera gets to send the photographs through a different pipeline and it throws away a lot of the pixel information as it converts to jpeg format. In RAW you will notice that your files are about 3 times as large as JPEG files from the same shot. Compression of the photograph is the reason. Data moves as bits in the processing engine and either it has to be moved or thrown away.

Jim