Surface gravity dependence of η_λ, α_λ, fixed point μ₁ and the normalized intensity at the fixed point, I_λ(μ₁)/2ℋ_λ, for the V spectral band. Plane-parallel model atmospheres are denoted by black crosses, and spherical model atmospheres are represented by other symbols. Filled red circles are T_eff = 3000 K, open green squares 4000 K, open blue circles 5000 K, downward pointing magenta triangles 6000 K and upward pointing pale blue triangles are 7000 K.