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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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