Hi,
the default convergence setting is zero for both.
Each plane itself have its own convergence setup, the values at the set up screen are to adjust this for all planes at same time.
Normaly you dont need to touch the Z value(up/down), the y value adjust the distance where the bullet streem cross, but since this values only adjust the preprogrammed comvergence setup there is no exact measurement.
btw, with the latest EAW1.28e exes the bullets lose speed with the distance(like real bullets), thats why its way harder to get long distance kills. On the other side its way more easy to aim at distances closer than 300m(900 feet).
Greetings,
Knegel