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A patent for two cinema lens optical formulas has been made public. Both formulas are for wide angle lenses, one is a 12-32mm t/3.5 and the other a 15.5-47mm t/2.8. NAB 2015 is just over a month away and we do expect at least one cinema lens announcement from Canon.
Full patent specs are after the break.
Patent Publication No. 2015-34858 (Google Translated)
- Published 2015.2.19
- Filing date 2013.8.8
Example 1
- Zoom ratio 2.50
- The focal length f = 12.50 18.75 31.25mm
- Fno. 3.50
- Half angle ω = 51.21 39.67 26.45 °
- Image height Y = 15.5mm
- Overall length of the lens 193.59
- BF 42.84
Example 2
- Zoom ratio 2.81
- Focal length 16.00 26.88 45.00
- Fno. 2.80
- Half angle of 44.18 30.05 19.06
- Image height Y = 15.5mm
- Overall length of the lens 247.38
- BF 43.27
Canon patent
- Negative positive and negative positive 4-group zoom
- Inner zoom (the second group)
- Inner focus (rear group of the first group)
Source: [Egami]
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