Canon patent describing an optical formula for a 6-22 mm f/1.4-1.8 lens for a 1/1.7″ sensor equipped camera. 6-22mm is 28-100mm equivalent on full-frame sensors.
The Canon [shoplink 30519]PowerShot G3 X[/shoplink] and Powershot S110 are equipped with a 1/1.7″ sensor (as other Canon Powershots), so I guess this patent is possibly referring to a future Powershot model.
- Patent publication number 2016 – 191753
- Release date 2016.11.10
- Application date 2015.3.31
- Example 1
- Zoom ratio 3.43
- Focal length 6.15 20.03 21.08
- F number 1.44 1.85 1.85
- Viewing angle 37.08 13.06 12.43
- Image height 4.65 4.65 4.65
- Length Total length 74.93 77.34 76.67
- BF 3.98 3.98 3.98
And the usual excerpt from the patent literature:
[Claim(s)]
[Claim 1]
In a zoom lens which performs variable power by having the 1st positive lens group and the 2nd negative lens group, having the 3rd positive lens group and a lens group of succession to the image side, and changing air spacing of each lens group from the object side,
setting air spacing of the aforementioned 1 lens group and said 2nd lens group to telephoto end — a wide angle end — largely
setting air spacing of said 2nd lens group and said 3rd lens group to a wide angle end — telephoto end — largely
Said 1st lens group consists of two lenses, one negative lens and positive lens,
Said 2nd lens group comprises five lenses containing three negative lenses and two positive lenses, and. Said 2nd lens group is 21 lenses more negative than the object side, 22 negative lenses, and 23 positive lenses. A zoom lens comprising a following lens, and said 22 negative lenses and 23 positive lenses comprising a cemented lens which has the plane of composition which turned a convex to the object side, and satisfying the following conditional expressions.
2.5 <f22/f2< 4.0
-7.0 <f23/f2< -3.0
25 <nu22-nu23< 55
f2: A focal distance of the 2nd lens group
f22: A focal distance of the 22nd lens
f23: A focal distance of the 23rd lens
nu 22: An Abbe number of the 22nd lens
nu 23: An Abbe number of the 23rd lens
[Claim 2]
The zoom lens according to claim 1, wherein said 2nd negative lens group comprises five lenses, 21 lenses more negative than the object side, 22 negative lenses, 23 positive lenses, 24 negative lenses, and 25 positive lenses, and it satisfies the following conditional expressions.
9 <f1/ fw < 14
-2.5 <f2/fw< -1.0
f1: A focal distance of the 1st lens group
fw: A focal distance of a wide angle end
[Claim 3]
The zoom lens according to claim 1 or 2 comprising an object side by the 1st positive lens group of the above, said 2nd negative lens group, the 3rd positive lens group of the above, the 4th negative lens group, and the 5th positive lens group.
[Claim 4]
The zoom lens according to claim 1 or 2 which object sides being consisted of by the 1st positive lens group of the above, said 2nd negative lens group, the 3rd positive lens group of the above, the 4th negative lens group, the 5th negative lens group, and the 6th positive lens group.
[Claim 5]
The zoom lens according to any one of claims 1 to 4, wherein the 1st positive lens group of the above comprises a cemented lens which joined the 11th lens more negative than the object side and the 12th positive lens.
[Claim 6]
The 3rd positive lens group of the above is the 31st positive lens, the 32nd negative lens, and the 33rd positive lens. The zoom lens according to any one of claims 1 to 5 having composition which comprised the 34th negative lens and the 35th positive lens, joined said 32nd lens and the 33rd lens, and joined the 34th lens and the 35th lens, respectively.
[Claim 7]
The zoom lens according to claim 3 or 4 constituting said 4th negative lens group from three sheets, the 41st positive lens, the 42nd negative lens, and the 43rd negative lens.
[Claim 8]
An imaging device provided with the zoom lens according to any one of claims 1 to 7.
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