Eight scales of light, not one blur
Real lenses don’t scatter light in a neat Gaussian — they throw a tight core with a long, faint tail that reaches clear across the frame. Lumen builds its bloom from eight cascaded blurs at geometric scales, summed under a single Falloff curve. Drop Falloff and the energy spreads into wide atmospheric haze. Raise it and the bloom collapses to tight halation hugging your highlights. One dial, the entire vocabulary of lens bloom.