Patent: Canon EF 180mm f/3.5 DO Macro

Patent: Canon EF 180mm f/3.5 DO Macro

This is the first I have seen this sort of patent. Canon has filed an optical formula patent for a diffractive optic macro lens. What better lens to upgrade with a DO version than the long-in-the-tooth Canon EF 180 f/3.5L Macro?

Patent Information (Google Translated)

  • Patent Publication No. 2014-137484
    • Publication date 2014.7.28
    • Filing date 2013.1.17
  • Example 1
    • Focal length f = 180.00mm
    • Shooting magnification ∞ 0.5x 1.0x
    • Fno. 3.50-4.50-5.20
    • Half angle ω = 6.85 °
    • Image height 21.64mm
    • The overall length of the lens 202.38mm
    • BF 52.18mm

Source: [EG]

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