One of the compound guys at the club where I used to shoot went to the Worlds at New York as part of the England Team. At the time the fashion was to have a large black dot on the scope lens. About 4-5 mm diameter. The idea was, if the gold was hidden behind the dot, you were on aim. Took some of the sensitivity out of the "view" as it didn't change so obviously when wandering slightly. If the gold appeared then you were in need of some adjustment.