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Old Sep 24, 2006, 12:14 PM   #1
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just purchasded a card off ebay - it has the proper capacity but would like to check its performance - any way to do this?

Thanks Calvin
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Old Sep 24, 2006, 12:44 PM   #2
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You can do your own tests by using a card reader and writing files to it to time writes.

Then, do the same thing to time reads.

For example, if you write 500MB of data to a card and it takes 50 seconds to complete, then write speed is approximately 10MB/Second. You'd need to turn off write caching to the reader for accurate test results (you'll find an "Optimize for Quick Removal" selection in most card's drivers if you right click on a card reader under "My Computer" and dig around under properties that disables write caching to the card).

There are also some utilities around to test performance.

But, the card reader can be a bottleneck (as can the speed of your PC, USB Port, etc.). So, it's only going to give you a general idea of the card's speed, in the device you're using it in, with the file sizes you're writing.

With most cards, read performance is better than write performance.

When a card is used in a camera, the bottleneck is usually the camera. In other words, you may have a card that's capable of 20MB/Second performance, yet only get 1 or 2MB/second from your camera. That's because the speed of the camera's interface to media is typically much slower than a fast card is capable of delivering.

So, with most non-DSLR models, you tend to get diminishing returns with a faster card (a card that's twice as fast, may only give you a small increase in performance).

AFAIK, the camera with the fastest interface to media right this minute is the Sony DSLR-A100.

It can write at approximatley 14MB/Second to a fast card like a Sandisk Extreme III. Most faster DSLR models are going to be limited to around 8 or 9MB/Second, and some entry level DSLR models usually top out at around 3 to 5MB/second, regardless of how fast the card is.

But, card performance isn't the only factor to look at. Some camera models have larger buffers (fast internal memory) that can store more images before the camera slows down once it hits a bottleneck writing to media. So, if a camera has a larger internal buffer, you may not need a fast card, depending on what you're shooting (raw or jpeg, number of photos in row you need to shoot before pausing).

Rob Galbraith has some performance tests here of how cards perform in some of the popular Canon and Nikon DSLR models, and also includes some card reader tests:


There's a database of card speeds in KM and Sony DSLR models here:


Also note that a card that's fast in one camera may not be as fast in another camera. There can be some differences in the way a camera communicates with a card impacting performance.

For example, a Kingston Elite Pro card is one of the slowest cards you can buy for use in KM DSLR models, even though it's not too bad in Canon DSLR models. I've got a 4x (not 40x) Lexar Card that tests about 5 times as fast as a 50x Kingston Elite Pro Card in a Konica Minolta Maxxum 5D. But, if you compared the same two cards in a Canon DSLR model, you may get the opposite results.

As a general rule, the higher end Lexar and Sandisk cards tend to work relatively well in most camera models. With the "off brands", you tend to take your chances with compatiblity. So, for best performance, it's a good idea to check with other users of a camera to see how well a given card works in it, if you can't find any controlled conditions tests for a particular camera/card combination.

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Old Sep 24, 2006, 1:34 PM   #3
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thanks for the help Calvin

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