So a few weeks back, I bought an Olympus E-5 — the idea being that I’ll play around with it and the E-3 (for side-by-side comparisons) for a little while, then sell the E-3 on eBay in order to help pay for the new gear.

Meanwhile, since the E-5 shoots bigger images (in pixel terms) than the E-3, I thought I should also upgrade from 8GB memory cards to 16GB cards for the new camera.

Now like everybody, I’ve had occasional camera memory card failures. I’ve managed to salvage all my images to date, but as the result of my experiences I’m relatively cautious about my use of memory cards. When I’m on a trip, I take 3 cards, and cycle through them daily — this way if a card dies (or my camera is stolen), I’ll lose at most 1/3 of the images I’ve taken. I also back up my images, but that’s the subject of another post. Anyway, to be even more cautious, I also prefer to use cards from different manufacturers (just in case somebody had a bad day at the factory, and a batch of “weak” cards made it out to retail).

A side benefit of this approach is that I’m now pretty well equipped to compare the actual write speed of multiple card vendors. Since the E-5 now has one slot each for compact flash and SD cards, I thought I might as well test the write speed of my fastest cards of both types.

My testing approach was pretty simple. The E-5’s buffer will hold about 9 Raw images — at 5 frames/sec, this means differences in memory card speed won’t show up until I’ve been shooting for at least 2 seconds. So for each card, I did rapid-fire shooting (high-speed continuous mode, manual focus, 1/8000 sec shutter, NR/NF off) — and tested how many images would get taken / saved in 5 seconds and in 20 seconds. Subtract the two, and you can calculate the actual captured frame rate (images / sec) and data write speed (MB/sec) for the card. I did 3 runs of each test so that averaging the numbers would smooth out my reaction time (I was timing things with my watch).

Anyway, here are the results:

As you can see, SanDisk is by far the speed champion of these three brands — either for CF or SD format. They also seem to have the most honest appraisal of card speed (although to some degree this is also impacted by the camera). Delkin is (surprisingly) slow for CF — there’s statistically no difference between their CF and SD cards (not the ones I tested, anyway). This came as a shock to me, given that comparable-grade CF and SD cards from most manufacturers show a 2x or 3x difference in speed.

Also, note that to keep cost comparisons “fair,” I used Amazon (on 15 January, 2011) as the single source of price data — I won’t pretend that these are necessarily the cheapest prices you could find anywhere. And thanks to the fact that I’m not independently wealthy, my data is obviously limited in the number of brands I could test.

So if you need to take sequential shots at a reasonably high frame rate (about the only time you’d care a whole lot about these numbers), hopefully this data will help you make buying choices that make the most sense to you.