EMSD8GO2I haven’t had a good juicy nerd/tech post in quite a while, so I figured I was due.

So a few weeks ago I needed to buy a SD card for a video camera and I wasn’t sure what to get. I asked around and not a lot of people seemed to know what I was talking about, so I did a little research and I thought I’d share it with you, just in case you ever find yourself in the same position as me.

Need a SD card for your camera? You’ve probably bought one of these before. I’ve probably bought a dozen or so. I’ve got a few for my camera (although I use my eye-fi card exclusively now), one for my Wii and others float around for various uses.

So what do you look at when determining with card to buy?

  • Price? You should. They vary quiet a bit. I like to shop around and you’ll almost always get a better deal online than in the store.
  • Size? Of course. Why settle for 4GB when you can get 8GB? Right?
  • Speed? Come again? What do you mean with speed?

A little known fact about these SD cards is that they have read and write speeds and this does matter at times. This was the question that I was asking that no one knew the answer for. I just bought a HD video camera that records directly to a SD card. I wanted to know if it mattered what speed the card was. Most people I asked didn’t know about speed. So here’s what you need to know.

SD cards divide their card’s speeds by “classes.” A class 2 card writes data at a rate of 2MB per second. A class 4 card writes data to the card at 4MB per second. You ever wish you could hit the shutter button and take pictures in quick succession? Well, you’re camera may not be designed to do that, but depending on your card, it might be impossible. If you’ve got a Class 4 card with a 6 Mega Pixel camera, it’s going to take a second or two to write the data to your card every time you take a picture. Make sense?

What about a video camera? Well, if you’re recording in HD, you have to figure out how many MB per second your camera writes HD video to the card and make sure you get a card that can handle that speed. If you’re card can’t handle the speed, then it either won’t work or your camera will record the video at a lower quality.

So, when buying an SD card, know what you’re getting. For your digital camera, you really don’t need a Class 4, 6 or 8 card. Save your money. However, when it comes to HD video, you need to plan for a Class 6 or Class 8 card to get the best performance. Check the documentation that came with your equipment as well just to make sure.

Read up for yourself here.