Canon has filed a new patent in Japan for the the 300mm f/4 IS, 24mm f/2.8, and 50mm f/1.3 lenses.
The patent describes a new Canon 300mm f/4 IS lens that includes an improved refractive index distribution element. Along with the 300mm f/4 IS lens, the patent application also mentions about a new EF 24mm f/2.8 and a 50mm f/1.3 lens models.
The lenses described in the patent feature an optical unit with an optimised refractive index distribution over the lens’ optics. The described optical system consists of a first lens unit with positive refracting power, a second lens unit with negative refracting power, and a third lens unit that has positive refracting power. See the image below.
Canon 300mm f/4 IS, 24mm f/2.8, and 50mm f/1.3 Lens Patent
- Patent Publication No. 2015-28551
- Published 2015.2.12
- Filing date 2013.7.30
- Example
embodiment Example Focal distance Fno. Half angle Image height Overall length of the lens BF One 294.00 4.14 4.21 21.64 239.07 83.42 Two 24.48 2.86 41.47 21.64 92.00 38.00 Three 51.70 1.30 22.71 21.64 94.01 37.50 Four 294.00 4.14 4.21 21.64 240.00 82.95 Five 6.15 20.45 71.28 2.88 3.71 3.69 30.34 9.98 2.89 3.60 84.11 86.12 90.41 11.74 15.68 8.50 Six 293.97 4.14 4.21 21.64 239.98 85.34 - Canon patent
- The use of refractive index distribution element
via Egami
