Sandisk SDHC speeds & fakes with Canon 500D

Ryaninja

Standard Member
I've recently bought an 8gb Sandisk Extreme 30mb/s edition SDHC card (class 10) from an apparently reputable dealer on ebay. It came in sealed retail packaging, and looks like the genuine article.

However in my new Canon EOS 500D the speed and number of shots taken is pretty much identical to the Sandisk 4Gb Ultra II (class 2) card I already own.

I did a number of tests to find out how many shots the camera would take and how fast using each card and rougly worked out an average. I repeated the tests with both large jpg and raw file, but not jpg+raw at the same time. I first formatted the card in the camera (low level checked on), then I set the camera to creative auto, turned off the flash, and set continous shooting on.

Both cards performed about the same, with each taking about 8-9 raw files before slowing down considerably, and around 30 jpegs before the same slowdown. Also, the raw file continuous shooting was noticeably slower than the jpegs. I wasn't timing, so I can't tell you exactly, but reviews I've read of the 500D say that the shooting speeds are almost identical.

However, I'm sure I'm not getting 3.2 shots per second either. I doubt I'd have to lower the resolution (from max) to get faster speeds on a DSLR such as this, although I don't know for certain yet as I didn't have time to carry out those tests, and also because I suspected they wouldn't be any different.

I thought about the possibility of a fake card, so I contacted Sandisk on their US site and had a IM style chat with someone there who confirmed that the serial number matches one of their products, and that my card appears to be genuine from the serial, capacity, model number, and actual description of the card.

I then tested the two cards on my PC, using a Hama 35-in-1 udma card reader over usb. It says on the front it'll transfer up to 32mb/s, although I have found the odd test that suggested they got 20mb/s, although I have to admit I don't know what cards they were using.

Anyway, here are the tests results generated by H2testw, a little app that generates 2gb random .h2w files to fill up the card and then verifies the data, all whilst recording the data transfer rate.

Sandisk 4gb Ultra II (class 2):
=============================================================
Test finished without errors.
You can now delete the test files *.h2w or verify them again.
Writing speed: 14.3 MByte/s
Reading speed: 16.5 MByte/s
H2testw v1.4
=============================================================

Sandisk 8Gb Extreme 30mb/s (class 10)
=============================================================
Warning: Only 7559 of 7560 MByte tested.
Test finished without errors.
You can now delete the test files *.h2w or verify them again.
Writing speed: 14.5 MByte/s
Reading speed: 17.0 MByte/s
H2testw v1.4
=============================================================

So (eventually!) I get to my question:

Do you think I have a fake or faulty card? Should I send it back as faulty/fake? It seems a little much to believe that both the camera and the card reader are at their limits, as I have seen data suggesting they are capable of more than I have been able to get in my tests, as already explained.

What do you think I should do? I'm considering buying the sandisk desktop reader or possibly the lexar one (can't remember the model numbers), but I've already spent loads of cash on the canon, lenses, and cards, if possible I don't really want to spend any more. I'm just wondering if anyone else has the same set of kit or similar and have the same issues? I probably should have spent the premium wonga and bought a card from a local retailer, but it's too late for that now!

Just for a note, my PC is
dell xps m1710 machine with a 2.8mhz dual core, 3gb of ram and a 7200rpm hard drive, so should be more than up to the test.

Thanks for reading if you made it this far! :)
 

alggomas

Standard Member
As far as I know all the write speeds etc vary depending on the temperture/type of reader and photographs taken.
It could be a dud,not a fake. If the capacity on the card is 8gb. Go to my computer find the card reader you are using,right click and go to properties.This should tell you the capacity.
Please bear in mind all these figures you read are not exact and are "advertising" figures in ideal conditions.
Look at a HD. Even if it says 100GB you will find it is about 90 or so as indexing and other stuff is on the HD.
 

weetsie

Well-known Member
like i said in the last thread, don't but flash off ebay.

sometimes you get memory that is of smaller capacity but appears larger in an OS until you hit the actual capacity and it will stop writing and sometimes you get cards that are the cheapest generic cards rebranded as high speed cards.

send it back, recorded and push for a refund and eventually you will get one.

EDIT: what i dont get is a class 10 card should write at 80Mb/s and a class 2 card at 16Mb/s but both your cards are doing well over 100Mb/s
 
Last edited:

ArmitageShanks

Well-known Member
EDIT: what i dont get is a class 10 card should write at 80Mb/s and a class 2 card at 16Mb/s but both your cards are doing well over 100Mb/s
16 Mb/s (2MB/s) and 80Mb/s (10MB/s) are the minimum guaranteed tranfer speeds, not the maximum.

The more expensive SanDisk Extremes can exceed those rates (admittedly I've never tried), but the hardware needs to be up to the challenge - probably the reason the SD consortium doesn't market a "class 30" card...yet.

My gut would say that you're hitting the limit of the camera and perhaps your USB hub or reader. I guess the only way to be sure is to find another memory card that proves that the USB reader can exceed what you're seeing with the Extreme card on your PC? Or try the USB reader and card on a different PC setup to see if you get similar results?

Probably easier to just buy another 30MB/s card from a reputable source and compare the two :)
 

Calzor Suzay

Active Member
From DPReview...

Method Transfer rate
EOS 500D USB 2.0 11.0 MB/sec
Sandisk Extreme III (using built in USB connector) 20.2 MB/sec
SanDisk Extreme III in USB 2.0 reader 11.3 MB/sec
 

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