If you are shooting in regular uncropped mode in continous high or low, it doesn't matter which; if you have fired off a few shots and the buffer is writing to the CF card, you can only continue in full uncropped mode. If you try to switch to Cropped mode while the buffer is being written to the card, you can not continue to shoot the camera until the buffer is empty. Moral of the story? Don't try to switch to Cropped mode while shooting continuous frames. Make sure there's a pause in the action (and the buffer is empty) before switching back and forth between Crop & Normal mode.