fun = @(w,qa) (9*w.^4.*cos(qa))/28000000 - (33*w.^2.*cos(qa))/32000 - (105*cos(qa))/64 + (603*w.^2)/2560000 - (4891*w.^4)/4480000000 + (93*w.^6)/560000000000 + 105/64;
fimplicit(fun)
You can tell fimplicit how far out to go of course.
fimplicit(fun,[-100 100 -100 100])
It does appear as if much is happening when you broaden the view.