
Originally Posted by
szichri
Why Canon has white lenses? First, the "white" color of the longer Canon L lenses is not white, it is more along the lines of beige to light gray.
The first is that, for several different very technically sound reasons, temperature swings are bad for lenses. Some materials used in some L lenses are more temperature sensitive. Canon has managed to get the flourite glass it uses to be more tolerant of heat, but it's still really brittle as well. A lens (any lens, with any lens elements) can be designed, built, and calibrated at any temperature in which it will continue to function. One of the characteristics of fluorite is that gas bubbles can form inside it if the temperature exceeds 50°C - 55°C. Canon went to the white barrels after having problems with some of their very early fluorite lenses.
But the further you get from this "calibration" temperature the less well it will perform. Light colored objects absorb heat energy less quickly in the sun. So a lens calibrated to work at an average daily temperature will experience smaller, and slower, temperature swings when used in direct sunlight. Why do they not make all L lenses light colored then? This effect is more pronounced with longer focal lengths and with zooms. Also, focal lengths over 200mm are seldom used in the studio...where the light colored lens might possibly cause reflection issues.
The second reason is, quite naturally, marketing. When you see all those big light colored lenses at a prefessional sporting event or a motor event most photographers immediately think "Canon". While the technical reasoning may be strong, Canon would be stupid not to also be thinking of the marketing and brand recognition value.
Heat impacting thermal expansion of the optics was the main reason, but photographers were also complaining about the lens barrels being too hot to hold comfortably. Canon had to do this due to the type of glass they were using in their first generation L lenses. Just happened to become their signature look.
Eh bakit ang Nikon meron ding white lenses? Nikon called it Gray Lens as opposed to Canon. The reason? Nikon's ED glass does not suffer from this problem, but the heat can cause metal components to expand and slightly shift the focus of the lens. That's why long lenses focus past infinity, to allow the focus to be corrected for expansion of the lens barrel.