The body is made of magnesium.
Air has a permeability of 1.000 000 37
Magnesium has a permiability of 1.000 12
Steel and iron are around 100
Mu-Metal, used for electromagnet shielding, is around 20,000 to 50,000
Think of permeability as the materials ability to react to (attenuate) radio signals.
In other words, the magnesium body is for all practical purposes, transparent to electromagnetic waves (radio)..... and even if it wasn't, there are dozens of holes through the metal shell.QuoteIt has been a long time sense I took electrodynamics courses in collage but this just did not sound right. This is true for the magnetic quality but magnesium is still conductive. Air is not. In fact aluminum is used for EMI shielding all the time and it has a permeability of 1.000021. This is greatly dependent on frequency at 2.4 Ghz the penetration of electromagnetic waves or skin depth of magnesium is only around 5.7 micro-meter. I would say that you will need a RF window for any wireless to work. I imagine that 800 Mhz would just go right through it. But we are talking wireless so that is 2.4 Ghz or higher. Just because something is not magnetic does not mean that it is a poor at EMI shielding.
If you do not want to take my word for it I found a like to a company that makes magnesium alloy casting touting EMI shielding as one of the advantages. It is named Wellcharter. The site will not let me post the link here.
This kinda rings true with me: I don't think Canon would have used a plastic top plate on a $2000 camera unless there was a good reason for it.