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More lens patents
This is an interesting DO patent from Canon. There seems to be a lot of them showing up, but no new DO products in a long while.
I've been told the lack of an A+ filterable wide angle from Canon for a full frame camera will be addressed sooner than later. Yes, there's Zeiss, but most want AF.
Patent Publication No. 2011-145518
- Release Date 2011.7.28
- Filing date 2010.1.15
Example 1
- Focal length f = 16.48 – 24.00 – 33.95 mm
- Fno = 2.91
- Half angle of 52.70 – 42.04 – 32.51 °
- 4 aspherical surfaces
- Zoom Ratio 2.06
- Four-group zoom lens plus a negative sign
- Second lens focusing is performed by Inner Focus
- Solve various problems using the diffractive optical element
- The astigmatism of the telephoto kept in order, to increase the refractive index of the positive lens
- A high refractive index, chromatic aberration occurs
- Aberration and astigmatism in the center of the telephoto image has a correlation, it is difficult to simultaneously correct
- Made achromatic diffractive optical element, a positive lens astigmatism correcting high refractive index
Source [EG]
cr
