I measured the luminosity of a white surface with seven different yellow filter glasses and a photometer with two different sensitivities, which resembled the photopic and scotopic sensitivity of a Commission Internationale d'Eclairage standard observer. When measured with filters GG 400, GG 420, GG 435, and GG 455, there was a small and almost equal reduction in the relative photopic and scotopic luminosities. Measured with filters GG 475, GG 495, and OG 515, there was a more marked reduction in the scotopic luminosities than in the photopic luminosities.