Canon EOS Rebel T1i EOS REBEL T1i/EOS 500D Instruction Manual - Page 41

3 Formatting the Card Execute [Format] in the following cases: The card is new. The card was formatted by a different camera or a computer. The card is full with images or data. A card-related error is displayed (p.209). About Low-level Formatting Do low-level formatting if the card's recording or reading speed seems slow. Since low-level formatting will erase all recordable sectors in the card, the formatting will take slightly longer than normal formatting. You can stop the low-level formatting by selecting [Cancel]. Even in this case, normal formatting will have been completed and you can use the card as usual. When the card is formatted or data is erased, only the file management information is changed. The actual data is not completely erased. Be aware of this when selling or discarding the card. When discarding the card, execute low-level formatting or destroy the card physically to prevent the data from being leaked. The card capacity displayed on the card format screen might be smaller than the capacity indicated on the card. 41