Technology for Durability and Toughness

Heat Shield Coating

Our endeavors to address heat in our traditional white lenses have reached a new stage. To reliably deliver outstanding optical performance under conditions of hot sunlight, Canon has adopted heat-reflecting white, not black, for our lens barrels. This history stretches back to the FD600mm f/4.5 S.S.C and FD800mm f/5.6 S.S.C., two large-aperture telephoto lenses released in 1976 for single-lens reflex cameras.* Our in-house development of heat shield coatings was an initiative to improve the reliability of our lenses with respect to temperature, and to advance the evolution of our white lenses. Through trial-and-error research into the selection and composition ratio of coating components, we heightened reflectivity toward the infrared rays in sunlight and developed new technologies that suppress temperature rise in the coating film and in coated items. This has enabled white lenses with enhanced reliability under harsh sunlight.

Our heat shield coating uses infrared reflecting pigments to enhance infrared reflection in sunlight. In the past, we had adjusted the color through the black of carbon black and the white of titanium oxide. However, carbon black strongly absorbs infrared rays, placing restrictions on the improvement of reflectivity. Our newly developed heat shield coating enhances reflectivity through tone mixing that replaces carbon black with infrared reflecting pigments. The coating exhibits outstanding resistance to UV weathering by using titanium oxide with a silica covering. It is also highly resistant to scratching and to damage from sliding. Our new coating pursues coloring that retains Canon’s signature white color. Heralding a new age for our white lenses, this heat shield coating was first introduced in the EF400mm f/2.8L IS III USM and EF600mm f/4L IS III USM.

*For single lens reflex cameras lenses. Also adopted in the TV2000mm f/11 super telephoto lens for broadcast cameras, launched in 1960.

Conventional white coating

Heat shield coating