[Patent] Canon Files Patent For 600mm f/5.6 and 800mm f/5.6
Egami (machine translated) found a patent filed by Canon for a 600mm and a 800mm f/5.6 lens using diffractive optical elements.
- Patent Publication No. 2012-123152
- 2012.6.28 Release Date
- 2010.12.8 filing date
- Example 1
- Focal length f = 584.99mm
- Fno. 5.80
- Half angle of 2.12 deg.
- Image height 21.64mm
- Length 360.03mm
- BF 94.84mm
- 17 pieces in 10 groups Lens Construction
- 3 UD glass sheet
- One fluorite
- A surface diffraction plane
- Example 3
- Focal length f = 779.00mm
- Fno. 5.80
- Half angle of 1.59 deg.
- Image height 21.64mm
- Length 462.02mm
- BF 120.29mm
- 17 pieces in 10 groups Lens Construction
- 2 UD glass sheet
- Two fluorite
- A surface diffraction plane
- Low dispersion material with anomalous partial dispersion
- To be effective in the correction of chromatic aberration
- Specific gravity is large (heavy)
- 3.18 fluorite
- FK01 3.63
- The specific gravity of small anomalous partial dispersion glass material
- FK5 2.46
- BK7 2.52
- Surface may be damaged easily
- FK01 is fragile due to temperature changes and large diameter
- Diffractive optical element (DOE)
- To be effective in the correction of chromatic aberration
- Is generated by unwanted light flare and ghosting
- Canon’s patented
- Become positive from negative to DOE
- DOE to place the position is hard to unwanted light incident
