If it's an SLR, you do, in that you block the stray light that can go in through the viewfinder, which is perhaps the counterpart of the wifi signal emitted by

If it's an SLR, you do, in that you block the stray light that can go in through the viewfinder, which is perhaps the counterpart of the wifi signal emitted by the netbook in your analogy. Most photo enthusiasts and professionals will block their SLR viewfinders when doing long exposures during which they aren't looking through the viewfinder, and pretty much every SLR comes with an eyepiece cover.