Most camera manufacturers actually recommend (or specify) that the card be formatted while in the camera. Formatting it there will delete all the photos. So, check your camera's manual on how to do this if you do not want to use Disk Utility.
Most camera manufacturers actually recommend (or specify) that the card be formatted while in the camera. Formatting it there will delete all the photos. So, check your camera's manual on how to do this if you do not want to use Disk Utility.