Egami spotted a new patent filed by Canon. The patent describes diffractive optical (DO) lens of the 180mm f/3.5 macro lens.
Canon lenses which feature the diffractive optical (DO) are smaller and lighter compared to the same focal length lenses but the price becomes generally higher when the lenses have optical formual for DO.
Canon currently sells EF 180mm f3.5L Macro USM lens with a price tag for $1,579.
Canon Patent For 180mm f/3.5 DO Macro Lens
- Patent Publication No. 2014-137484
- Published 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
- Effective diameter of the front lens 58.18mm
- 12 sheets 8 groups lens configuration