The red line around the barrel of a Canon L-series lens depicts more than just a high level of professional image quality. It also indicates a Herculean level of human endeavour, as well as ground-breaking design and manufacturing input, particularly where the glass is concerned. As the Canon L lens timeline below shows, its development has introduced the first artificial crystal fluorite glass in a lens, high-precision aspheric lens manufacture, extra-wide apertures, unprecedented angles of view, the world's first superzoom lens and anti-reflection coatings with a structure finer than the wavelength of visible light.

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