Rebel T1i (500D) and SDHC Class 6 Card Question

How important is it to have a Class 6 SDHC card for recording video? All my SDHC cards seem to be Class 2 (2 Sandisk Extreme IIIs) and I have one Class 4... has anyone had any issues with these "slower" cards"?

Extreme III cards are more than fast enough, and if they were to re-certify them they could easily be Class 10 (which was finally approved). Basically you need a minimum speed faster than the data speed (plus an overhead, 10-20% is usually fine). For 720p video @30mpbs (18 min per 4gb file), you need 3.8mb/s minimum write speed. That means a true class 4 card (min 4mb/s) would be cutting it close, and class 6 is a bit of overkill (unless you go for the 45mbps 1080p, then that's getting close too). Luckily the sandisk ultra II 2008 edition or any extreme III, and lexar pro series, are all fast enough even if they were not certified. Other cards you can use at your own discretion if they are not certified for class 6 or higher, but I can't really tell you if it'll work.

Thanks so much for your quick response... Now that I've got the battery charged, I've tried out the cards without an issue... they seem to work great! In fact, they are Ultra II cards.. not Extreme III ... only 15mb/s... no issues at all with them...

Cheers!

just wondering how good sandisk Ultra II's are as I have (2) 16 gig ones
will i see any slowdowns

At least one T1i user had problems with Kingston Class (6) cards failing to keep up with the camera. A buffer bar would appear, fill up, and the video recording would "shut down". He was losing some video this way.

Figuring his two cards might be defective he returned one for a replacement, which did the very same thing. So he called Canon and a tech there told him the camera could be "brand" sensitive, recommended SanDisk Extreme III Class (6). He bought one and his problem went away.

I use SanDisk Extreme III Class (6) and have never had a problem. The Class (4) SanDisk Ultra II and PNY cards work fine in my HF100's but I won't risk losing any footage by trying them in my T1i.

I've heard of buffer overrun problems in Nikon video capable DSLR's also so I think the Extreme III Class (6) is a necessary safe practice.