What is the difference between an attack periscope and an observation periscope on a U-boat?
The field of view of observation scope was larger which made it handy for looking around. The attack periscope was built to have just enough FOV to be able to target ships with. Structurally, the obs scope was larger and was risky to use if enemy planes were though of being around due to the bigger chance of the ‘eye’ reflecting sunlight. Read more from here: http://www.uboataces.com/periscopes.
