What are the differences between shooting in AF-S and AF-C? What situations would you choose to shoot in one mode versus the other? I've always shot in AF-S mode but at a recent photo shoot, which was very dark, the focus wasn't always locking on in time to get the shot. Would using AF-C have helped do you think? In your experience are the amount of out of focus shots significantly higher when using one focus mode over the other? Any insight appreciated. Thanks.