Egami, the Japanese photography blog has discovered two patents Canon filed for a new EF 600mm f/4 lens. Suggestions have been made these lens may be aiming for the 2020 Summer Olympic Games in Tokyo and Rio de Janeiro in 2016. In my earlier post, I have made some observations on Canon and suggested they introduce more DO lens in the future. MichaelDanielHo.com
Patent Publication No. 2014-26210
- Publication date 2014.2.6
- Filing date 2012.7.30
Example 1
- Focal length f = 588mm
- Fno. 4.12
- Angle of view 2? = 4.22 °
- BF 56.0mm
- Total lens length 374.7mm
- Inner focus
Example 5
- Focal length f = 588mm
- Fno. 4.12
- Angle of view 2? = 4.22 °
- BF 55.0mm
- Total lens length 343.5mm
- Inner focus
- Diffraction optical element
Effect of the glass material
- Fluorite (Fluorite)
- In the long lens fluorite + total length, correction of chromatic aberration is easy
- In short lens fluorite + total length, correction of chromatic aberration is difficult
- Diffractive optical element (DOE)
- Diffractive optical element can be corrected if the chromatic aberration
- Flare caused by light diffraction
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