Field of View Calculator (Sensor + Focal Length) mechanism

Model scope

The core geometric formulas are standard after adding the explicit radians-to-degrees conversion and diagonal calculation. Final approval requires the exact preset dimension table, explicit positive-input constraints, and an honest label stating that 35mm equivalence uses the approximate 43.3 mm reference diagonal.

• The AOV formula is mathematically correct in radians, but the specification claims degree outputs without explicitly applying the radians-to-degrees conversion: AOV_degrees=2*atan(sensorDim/(2*f))*180/pi.
• The diagonal AOV requires sensorDiagonal=sqrt(sensorWidth^2+sensorHeight^2), but that required step is not stated.
• The 35mm-equivalent formula is valid only when 43.3 mm is intentionally used as the approximate 35mm image-circle diagonal; the exact full-frame diagonal is approximately 43.27 mm.

Units and conventions

• Sensor width, sensor height, focal length, and sensor diagonal must all use the same linear unit, conventionally millimeters.
• atan returns radians, so AOV values require multiplication by 180/pi to be reported in degrees.
• The 43.3 constant is in millimeters and represents an approximate 35mm-frame diagonal.
• Preset dimensions must be explicitly defined; APS-C and medium-format dimensions vary by manufacturer and format.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "sensor_width_mm": 36,
    "sensor_height_mm": 24,
    "focal_length_mm": 50
  },
  "expected_outputs": {
    "horizontal_aov_deg": 39.6,
    "vertical_aov_deg": 26.99,
    "diagonal_aov_deg": 46.79,
    "equivalent_focal_length_mm": 50.04
  },
  "working": "Diagonal=sqrt(36^2+24^2)=sqrt(1872)=43.2666 mm. Horizontal=2*atan(36/(2*50))*180/pi=2*atan(0.36)*180/pi=2*0.34556*57.2958=39.60 degrees. Vertical=2*atan(24/100)*180/pi=2*atan(0.24)*57.2958=2*0.23554*57.2958=26.99 degrees. Diagonal=2*atan(43.2666/100)*57.2958=2*atan(0.432666)*57.2958=46.79 degrees. Equivalent=50*(43.3/43.2666)=50.04 mm."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The zero-diagonal input causes the equivalent-focal-length calculation to divide by zero. The zero-width boundary also produces mathematically finite but physically invalid output, and a negative focal length yields signed negative AOVs unless explicitly rejected or normalized.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json