what does class 4 mean?
A class 4 card is a card rated through a system that determines overall write time speeds. A class 10 card is extremely fast and is used mostly for video A class 4 is a relatively slow card, but is fine for recording images from a consumer digital camera. You can use them interchangeably, a Class 10 card still works great in the cheapest digital camera. But it might be a waste if money is an issue. A class 4 card is fast enough for most digital cameras priced below, say, $300. It will not hurt anything to use a slow card in ANY camera that is not recording video. It only affects the time it takes for your camera's internal frame buffer to write to your card. The worst that could happen in a digital stil camera using a slow card is that you might have to wait a bit to shoot while it writes, and then usually only seconds.