Yeah. B.S. has a life of its own. People need to exercise a bit of common sense. If white was necessary, then ALL of the larger Canon L lenses would be white, but the 135 f/2 L and 200/2.8 L are BLACK, and always have been. People need to do a bit of thinking here as well; is sunlight the only way to collect heat? God no, no it is not: ambient air temperatures will eventually allow all lenses to reach the same, exact maximum heat. Again, the US military has done extensive testing on painted finishes. The simple science is that paint coloration does NOT prevent metal or glass items from gaining heat from sunlight. MASSIVE, $40,000 to $100,000 cinema lenses, like the huge Fuji zoom shown here last week (
Fujinon 25-300 mm T3.5 to 3.85 Cabrio Premier PL Lens ZK12X25 are almost ALL solid black. Same with ALL of Canon's cinema lenses...every single one of those are BLACK. If white offered a significant, real advantage, then all lens makers would make their lenses with a white or "putty" enamel painted finish, the way Canon does. Buuuuut....they do not. Sigma's monster 200-500mm f/2.8...is GREEN... Again, marketing B.S. is seldom truthful.
In normal air temperatures, from 25 degrees Farenheit to about 100 degree Farenheit, paint color has basically no real, significant impact on sunlight, and almost ZERO influence on ambient air temperature, either heating, or cooling. If white were TRULY better, ALL of the lens makers would make everything white.
Marketing is almost always BS. Look at what the cigarette companies said for years. Look at what car companies say about their products. Marketing is designed to sway public opinion. The way I read it is Canon's big lenses have a tough time handling sunlight...