Optical properties of carbon are studied in bulk state from λ ∿ 0.05 to 100 μm for graphite, and from λ ∿ 0.05 to 1000 μm for glassy carbon; in small particle state, the optical studies cover the spectral range going from λ ∿ 0.1 to 100 μm for all the materials. A Kramers-Kronig analysis of near normal reflectance data and/or a reflectance data fit to a Drude-Lorentz model gave bulk optical constants. These optical constants are used in theoretical calculations of extinction and the results compared with experimental results obtained from measurements of a variety of carbon particles. It is inferred that the high experimentally observed extinction is mainly due to a shape effect.