HC means hard coating. It is available for all lenses. The function of HC is to prevent lens from scratches and make lens surface smooth. It is also the basic coating for other coatings.

MC stands for multi-coating. The main function of MC is to improve lens' transmission rate by reducing reflections of visible light. And it also eliminates the fog of lens.

EMI means interfere electro magretic. This special coat is made to absorb harmful low frequency radiation and microwave. EMI lenses help the people who work long time in modern offices to resist radial pollution.