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Canon Patent Application For Speedbooster-like Focal Reducer

Canon Patent Application For Speedbooster-like Focal Reducer

Hi Lows Note spotted a Canon patent application 2019-003074 that describes a focal reducer.

A focal reducer does the opposite of a teleconverter, reduces the focal length and increases the lens aperture. You likely know that from the Metabone Speedboosters.

Specification and lens arrangement of master lens 1 (18-55mm, F2.8)
Zoom ratio: 3.05
Focal length: 17.50 – 53.35 mm
F number: 2.80 – 2.80
Half angle of view: 36.65 – 13.71 
Image height: 13.02 – 13.02 mm
Lens length: 148.81 – 172.70 mm
Back focus: 35.51 – 40.31 mm

Specification and lens arrangement of master lens 1 with reducer 1
Focal length: 11.36 mm
F number: 1.82
Half angle of view: 36.67 
Image height: 8.46 mm
Lens length: 142.26 mm
Back focus: 2.00 mm

Specification and lens arrangement of master lens 2 (34mm, F1.4)
Focal length: 34.20 mm
F number: 1.45
Half angle of view: 32.32 
Image height: 21.64 mm
Lens length: 129.16 mm
Back focus: 39.35 mm

Specification and lens arrangement of master lens 2 with reducer 5
Focal length: 23.92 mm
F number: 1.02
Half angle of view: 32.33 
Image height: 15.14 mm
Lens length: 125.59 mm
Back focus: 2.00 mm

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