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Canon EF 17-40 f/2.8-4L Patent
Below is a patent for a new Canon wide angle zoom concept. The variable aperture is interested, if it remained as light and compact as the current 17-40 f/4L, the additional stop of light wide open would be a nice feature.
Patent Publication No. 2010-42792
- 2012.3.1 Release Date
- 2010.8.20 filing date
Example 1
- 39.05mm – f = 17.64 focal length
- Fno = 2.64 – 4.10
- 28.99 deg – 50.80 half angle of view.
- Image height 21.64mm
- 136.70mm – 134.67 full-length lens
- BF 39.97 – 64.95mm
- Lens Construction 12 elements in 9 groups sheet
- 4 aspherical surface
Canon's patent
- Negative lead type zoom lens of negative-positive
- Small and light lens for focusing
- Inner focus
- Focusing the use (1b in the figure) part of the first lens group
- Video support
Source: [EG]
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