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World firsts

• The history of Canon lens development is described by a string of world-first technologies. These include:First commercialisation in 1987 of the Ultrasonic Motor (USM) for use in interchangeable SLR camera lenses. Now employed in the majority of EF lenses, USM provides high-speed, near-silent auto focus with good holding torque for accurate, rapid-response stopping with no overshoot.
  
• First appearance of an aspherical lens element in an interchangeable SLR lens, introduced to eliminate the spherical aberrations that soften the image quality of conventional lenses.
  
• First introduction of fluorite, UD (Ultra-dispersion) and Super UD lens elements in interchangeable SLR lenses in order to correct chromatic aberrations.
  
• First interchangeable lens to incorporate an Image Stabilizer (IS). Converted into shutter speed, the effect of Canon’s latest IS is to allow for handheld photography at about three stops less, with no perceptible increase in image blur. IS is now incorporated into twelve current model EF lenses.
  
• First and still the only company in the world to incorporate a diffractive optical (DO) element into an interchangeable SLR lens. Using diffraction rather than refraction as the primary means of focusing light, Canon’s EF400mm f/4 DO IS USM and EF70-300 f/4.5-5.6 DO IS USM lenses produce outstanding image quality, yet are significantly lighter and smaller than similarly specified conventional lenses.
  
• First 10x zoom (EF35-350mm f/3.5-5.6L USM)
  
• Longest focal length at largest aperture (EF1200mm f/5.6L USM)