How to Format an SD Card in a Mac Computer:
To have it work in a Moultrie Camera (including an A-5)
Insert your SD card into your Mac computer's SD card reader. If your Mac does not have a built-in SD card reader, you can purchase a card reader that plugs into the USB or port on your Mac. Alternately, with the camera off, connect a Mini USB cable connecting the camera and the USB port, then turn your camera to setup.
Click the "Go" button in the Mac menu and then click "Applications."
Double-click the "Utilities" folder within "Applications." Double-click the "Disk Utility" app icon to launch the application.
Select your SD card on the left side of the "Disk Utility" program. Click the "Erase" tab.
Click the drop-down box next to "Volume Format" and select the type of formatting for the SD card. Select format: "FAT" so that the SD card will work correctly with your Moultrie Camera. DO NOT SELECT "Mac OS Extended."
Type in a name for the SD card next to "Name." Click the "Erase" button to begin formatting the SD card. Wait for the "Format Complete" box to appear before disconnecting the SD card from your Mac. Drag the disk on the desktop to the trashcan or right click and select eject so you may remove/disconnect the SD Card/USB Cable. Remove the USB cable from the camera/insert the SD card into the camera if not already there and turn the camera to on. Proceed to use camera as normal.