I am new to the DSLR world and have just purchased the Canon 600D and Sigma 17-70mm macro. I have a Sandisk 16 GB SDHC card.....is this card too slow for video as each time I record I only get approx 30 seconds before it automatically stops. The indicator does appear on the right of the screen as a warning. If this card is too slow can anyone recommend a fast card for video and still shots? Any help appreciated.