Bit late for WWII consideration but this is from a 1950s USAF fighter tactics book:
BINOCULARS IN COMBAT
For both offensive and defensive reasons, pilots must not only be able to look around, but they must be able to recognize and interpret what they see. Aircraft recognition for Air-to-Air work and target identification on Air-Ground work are vital factors in effective offensive or defensive action. To help in the solving of these problems, there is one thing that will help you or your flight improve its Tactical effectiveness--as flight leader, keep a pair of binoculars with you at all times. They will save you precious time and fuel when you are able to distinguish the aircraft type that is 10,000 or 15,000 feet above you in the "cons". They are also useful in watching airfields for activity while you circle above the heavy flak altitude. They are useful when doing fight-bomber work for a closer look at haystacks, trees, and other things used to camouflage weapons, supplies, vehicles, troop concentrations and the like.