How Fast of a Class?

Solid state cameras are where it's at these days. Gone is the hassle with tape and its laborious real-time transfer speeds. With a memory card the encoding is done right in the camera and all you have to do is copy the resulting file. It's a great system that is the current standard right now, even in very inexpensive cameras.

Cheesycam is a great blog for DSLR DIY and alerts us to some great deals we can all use. Recently, they've been posting about the 32gb Transcend Class 10 SDHC memory card, a deal at B&H for $63.46. The "class" refers to the write speed, but I wonder what the actual advantage is. I've been using a 32gb Kingston Class 4 for a few years now (it gives me about 3 hours at the full bitrate on my Canon HFS100) and have never had a problem with the speed the video data gets to the card.

There is a 32gb Lexar model that is a dollar cheaper and uses the regular Class 4 speed. I'm not sure if Class 10 is really that much better or just a numbers game by the manufacturer ("10 is 2.5 times better than 4!"), so you might want to save a buck. Of course, getting a Class 10 may future-proof your cards for use in more modern cameras, but I guess only time will tell.



Unknown said…
Seems to me the class is in relation to the data transfer rate or rather the sustained data transfer rate. So a 4 can write at a sustained 4mb/second. The 10 can write at 10mb/second. With HD i would assume the higher the better. I just wonder if the card will run out of read/write cycles faster.

Is there an ideal rate? Do we know what HD's minimum class is? I may have to go google it.
Unknown said…
Ah. i also just found this. its worth the read. Especial on fragmentation:
Jake. said…
Certain cameras, such as the t2i, need at least a class 6 car otherwise the camera will overheat, cut off your video files early or shut the camera down entirely given that the computer inside is running too much info at once and the processor cant handle the cycles. So is a class 10 necessary? i dont think so. It all depends on what camera you own, and the manufacturer's suggestion. They dont want to see their products die or blow up any more than you do.
Unknown said…
A class 4 and 6 will get you through your frugal needs. The more pro your gear the higher class I would use to be safe. Ive used nothing under a class 4 and hadnt needed anything over a class 6, although with newer formats of cards coming out Im not sure if this info will be relevant for the long term. Doesnt SDXC have a different classification? said…
A Class 4 SD card is great for audio, but is lackluster for the data rate of many DSLRs. I've used nothing less than Class 10 for shooting.

The T2i has an issue with overheating as time goes on and the more you use the camera. I'm not sure it has anything to do with the cards used in production.