Folks, I’m still having trouble and don’t know why... When I received a new Lexas CF Card 256GB 1066x, I formatted the card in my camera (5DMK3). This works fine but I want to format to EX FAT by using Disk Utility in my Mac Book Pro retina... Unfortunately, I updated my OS X to El Capitan. Now when I try to erase and partition to EX FAT, I do not get the same results. When I insert the card back in my camera, the camera skips frames and will stop after a minute or so with no recording on the disk. So Please offer me advice how you folks with El Capitan are getting your CF Cards to work... What am I doing wrong? Thanks, Joe Ray at: joeray@alaska.net