Upload & Sell: Off
You need a HDMI port on your camera, I assume the 1Ds III doesn't have one.
I use a SmallHD DP-6 with my 1DsMkIII, use the composite cable that came with your camera, the "G" input of the RGB input of the monitor is the composite input of the monitor. No, it's not HD resolution, but it definitely helps with focusing in the studio. Great monitor.