[Patent] Canon Files Patent For 14mm f/2.8 Lens (better coating, low refractive index)

14mm f/2.8

Egami (translated) spotted another patent filed by Canon. This time it is for a 14mm f/2.8 lens with improved coating (tubular coating):

It seems it is possible to realize a low-refractive-index low reflectivity by the structure below the diffraction limit, even without the uneven surface of the coating. 14mm F2.8 is what I want you to adopt all means patent coating of the lens as the front lens is large, yet is protruding.

Cross-sectional view

  • Patent Publication No. 2012-159723
    • 2012.8.23 Release Date
    • 2011.2.1 filing date
  • Example 1
    • F = 14.3mm focal length
    • Fno. = 2.89
    • Half angle ω = 56.6 °
    • 14 images in 10 groups lens configuration
  • Existing coating roughness
    • In daily use, dirt or dust may adhere, could not wipe, sex or bad Mentenasu productivity and manufacturing process
  • Canon patent
    • (Coating applied to one surface of a lens) thin film layer
    • Having a plurality of tubular spaces are arranged parallel to the tube
    • Maximum opening diameter of the tubular space below 400nm
    • The inorganic oxide materials (silica, titania)
[via Egami]