  We study exact renormalisation group equations for the 3d Ising universality
class. At the Wilson-Fisher fixed point, symmetric and antisymmetric
correction-to-scaling exponents are computed with high accuracy for an
optimised cutoff to leading order in the derivative expansion. Further results
are derived for other cutoffs including smooth, sharp and background field
cutoffs. An estimate for higher order corrections is given as well. We
establish that the leading antisymmetric corrections to scaling are strongly
subleading compared to the leading symmetric ones.
