To date, the only prosumer Canon DSLR that has WiFi is the EOS-6D full frame camera. Apparently, Canon has problem adding WiFi to other higher end models like the EOS-1D X, EOS-5D Mk III, EOS-7D Mk II because of the interference created by their magnesium bodies.
Now a discovery in one of Canon's patents may shed some light on this topic. Has Canon finally worked out the difficulties in adding connectivity to their higher end cameras? Will we see WiFi added to the upcoming EOS-1D X Mk II and EOS-5D Mk IV DSLRs?
US Patent US 9,113,062 B2
“Conventionally, there has been proposed a configuration of an imaging apparatus in which a wireless communication unit is arranged on the top side of a pentaprism in a finder section (see Japanese Patent Laid-Open No. 2008-244735). However, an accessory shoe for providing communication by being connected to an external device such as a strobe is provided on the visible face of an imaging apparatus.
Therefore, the metal section of the accessory shoe disturbs a radio wave to be emitted from or received by the antenna section of the wireless communication unit upon wireless communication, so that stable communication state cannot be obtained. In addition, the clearance between the wireless communication unit and the accessory shoe needs to be ensured, resulting in an undesirable increase in size in the height direction of the imaging apparatus.
Accordingly, Japanese Patent Laid-Open No. 2000-75381 discloses a configuration in which the wireless communication unit is arranged on the inclined surface (Dach surface) of the pentaprism such that the accessory shoe does not disturb a radio wave upon wireless communication.”