CF can only be formatted in the camera. If it cannot be formatted in the camera, first format it in the computer as FAT32, and then format it in the camera.
Two habitual judgments: 1. It is almost impossible for a machine in 2006 to recognize a card of more than 2G.2. When 512M cards were still sold, 99% of the machines purchased did not have 2G or more cards.It is estimated that your camera can recognize 2G at most,
