WiFi: Automatic backup

Many users of cameras like the EOS 50D and EOS 5D Mark II would like to be able to shoot to two memory cards at once as is possible with the EOS-1 series Mark III models. There is a way to do this using a WiFi unit. Simply attach either the Canon WFT-E3 or WFT-E4 WiFi units to the camera and connect a small 1.8inch USB hard disk drive to it. You can now select to save images to both the memory card and the external hard drive, and even choose to save different files to different places – for example, a RAW file to the CF card and a JPEG file to the USB hard drive.
EOS 5D Mark II