^ I too think we're talking about star bursts, there are no settings you can alter to create sun ray's, they are either there in reality made visible by mist or whatever, or they aren't.
Star bursts are created by small apertures, shoot at f9 or smaller.
You may get lens flare shooting in to the sun.
The fingers of a starburst mark the point in the lens that the diaphragm blades meet, a 6 blade diaphragm will produce 6 fingers, odd numbers double so a 7 will produce 14 fingers, I dunno why that is, I believe the shape of the blades also have an effect..:shrug: