Canon Patent for EF 70-400mm f/4.5-5.6L IS Lens

Egami discovered a new patent filed by Canon in Japan. The new patent describes a Canon EF 70-400 f/4.5-5.6L IS telephoto zoom lens. This new lens could be announced by the end of 2014 and will be a good replacement for the current EF 100-400mm f/4.5-5.6L IS USM lens model.

Canon EF 70-400mm f/4.5-5.6L IS lens is 240mm in overall length and provide a zoom of 5.45x. Focal range is between 71.33mm and 388.95mm. The lens design as we see from the patent details shows multiple elements divided in 6 groups.

Canon Patent for EF 70-400mm f/4.5-5.6L IS Lens


Description and self-interpretation of the patent literature
  • Patent Publication No. 2014-21256,2014-21257
    • Publication date 2014.2.3
    • Filing date 2012.7.18
  • Example 2
    • Zoom ratio 5.45
    • Focal length f = 71.33-144.71-388.95mm
    • Fno. 4.63-4.84-5.83
    • Half angle ω = 16.87-8.50-3.18 °
    • Image height Y = 21.64
    • 240.00-284.68-303.83mm overall length of the lens
    • BF 75.92-79.30-95.93mm
    • 6-group zoom of positive and negative positive and negative positive and negative
    • (Part of the fourth group) anti-vibration
    • Rear Focus (Group 6)

via EG

  • New lens at 70mm its aperture is 4.5
    100mm-400mm at 100mm its aperture is 4.5 , so with 70-400mm wont the aperture stop down ??