FOV Of Camera Spec Does Not Match Calculator

Just curious why the Data Sheet for some of these Hikvision cameras doesn't match up with what I get in any lense calculators.

From the Data Sheet for DS-2CE16D5T-IT3 (http://overseas.hikvision.com//uploadfile/image/20150721100447250.PDF):

Angle of view: 103.5° (2.8 mm), 80.9° (3.6 mm), 54.3° (6 mm), 24.3° (12 mm)

From the calculator: 80.9° (2.8 mm), 67.38° (3.6 mm), 43.60° (6 mm), 22.62° (12 mm)

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