Witam.

http://www.the-digital-picture.com/C...ns-Series.aspx

"Many in the Canon L lens series are white in color. According to Canon, this reduces heat gain when a lens is used in bright, direct sunlight. White reflects more light than black - thus, less heat gain."

http://terrychay.com/blog/article/th...ite-lens.shtml

"Why did Canon paint their lenses white? I think it’s because solar observatories and telescopes were painted white in order to keep the air inside at a steady temperature during the day."