Tutorial Video: Formatting Your SD Card: Mac
Sometimes, SD cards will need to be formatted before being used in particular devices.
Check your device’s manual before formatting a card to confirm you choose the correct format. Formatting any memory source will erase all data stored on it.
Please insert your SD card inside your computer's built in SD card port or or inside of a card reader that is plugged into your computer's USB port. Follow the steps below:
1) Open the Disk Utility application and select your SD card.
2) Select "Erase" from the submenu.
3) Choose either "FAT" Or "Mac OS Extended" from the re-format menu.
4) Wait for the format process to complete. Once it is finished, a notification will pop up. The SD card will now be empty and ready to record.