Canon Patent: More RF mount lenses, RF 27mm f/1.4 And RF 35mm f/1.4

And yet another Canon patent for RF-mount lenses spotted by asobinet.com. An RF 27mm f/1.4 and an RF 35mm f/1.4.

From the patent abstract:

In recent years, image pickup devices such as digital still cameras, video cameras, surveillance cameras, broadcasting cameras, and silver halide photography cameras using a solid-state image sensor have become more sophisticated. As an optical system used for this, the entire focus group is required to be miniaturized. Further, there is a demand for an optical system capable of satisfactorily correcting chromatic aberration, curvature of field, etc. at the time of shooting at the nearest distance while increasing the shooting magnification when focusing from infinity to the nearest distance. Further, with the shift to mirrorless large format cameras, there is a demand for a lens having a short back focus, a small size, and a large aperture. As an optical system that satisfies these requirements, a lens group having a positive refractive power, a focus lens group having a positive refractive power, and a focus lens group having a positive refractive power, which are arranged in order from the object side to the image side, are used.

It seems keeping thing small and light-weighted is a major topic in Canon’s R&D department.

Optical formulas for the 27mm lens:

Example 1

• Focal length 26.79
• F number 1.44
• Half angle of view (°) 38.93
• Image height 21.64
• Lens overall length 134.78
• BF 13.00

Example 2

• Focal length 26.62
• F number 1.44
• Half angle of view (°) 39.10
• Image height 21.64
• Lens overall length 131.96
• BF 20.00

Example 5

• Focal length 26.70
• F number 1.44
• Half angle of view (°) 39.02
• Image height 21.64
• Lens overall length 133.24
• BF 20.00

Optical formulas for the 35mm lens:

Example 3

• Focal length 33.73
• F number 1.44
• Half angle of view (°) 32.68
• Image height 21.64
• Lens overall length 143.92
• BF 20.00

Example 4

• Focal length 33.87
• F number 1.44
• Half angle of view (°) 32.57
• Image height 21.64
• Lens overall length 131.26
• BF 16.49