[Sailor Steve]

Real-Life: As RDP's link to Hitman's post points out, they actually had the same zoom levels. The attack scope's head was smaller, which made it harder to spot but also meant that it let in less light, so was useless at night. The Obersvation scope was better at night, but still not as good as a surface attack when it was really dark. As mentioned, the O-scope also cranked up almost 90 degrees to aid looking for planes before surfacing.

But the Observation scope's main advantage was location. The Attack scope was in the conning tower and had a powered rotating mechanism. The O-scope was in the control room where the captain could put it up now instead of having to climb up into the tower.

Of course that means nothing when you can press the 'F3' or 'O' button on a keyboard. To get a feel for what it really entails, don't use the keys, but use the mouse to actually make all the moves when you use the Attack Scope. Then you will see what the Observation Scope is really for.