Top critical review
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Fast at reading, significantly slower at writing
on 10 March 2014
I tested the read and write speeds of the SanDisk Extreme Pro (32GB) using the SD slot on an iMac and Drive Genius software. These are the results:
Sustained sequential read: 69.91MB/s
Random access read: 69.33MB/s
Sustained sequential write: 28.48MB/s
Random access write: 12.53MB/s
In other words, it doesn't look like I'll be seeing anything close to 95MB/s when recording RAW and video files on my camera. Transfer of these files from card to computer are, however, very fast. The low random access write speed suggests that this card would not be ideal for use as a computer boot disc, except for emergencies. I believe that slow random access write is a common problem with SD cards.
I've been using the card with my camera for a few weeks now, replacing a different card that was also Class 10. I've noticed that the camera performance has improved a little (fewer buffering delays) since I started using it, though not as much as I'd been hoping - which is why I ran the speed tests. I've only had one actual problem since using the card: it saved a JPEG but not the corresponding RAW for some reason. It's impossible to be sure whether this was a problem with the camera or the card, though it's the first time it's happened with this camera.
In conclusion, I feel that the card is a bit overpriced for the slight performance increase I've gained. As always, take the manufacturer's specs with a pinch of salt.