OK, so now it should read :-
Take exposure (A) for Landscape
Take Exposure (B) for Sky
Deduct (A) from (B) to give you "stop"(C) difference
Apply ND Grad with (C)-2 stops
Eg. For a 3 stop difference between Land & Sky, apply a 1 stop Filter. ......ish
Can you tell I don't use filters
