Drakegoodman scanned this 1917-ish photo of Soviet planespotters in exotic headgear; according to a commenter, the binox are focused at infinity “so that when you found the source of the sound by turning your head, you could see the aircraft creating that sound.”
I think the foot-wide-apart lenses will also make for headachingly good 3D viewing.
The guy at the right really is trying not to laugh, no?