Sunny 16 / Exposure Rule-of-Thumb Panel mechanism

Model scope

The full-sun Sunny 16 method is standard and the worked vectors are internally computable from their reference_data. Verdict is NEEDS_REVIEW because the specification does not provide a definitive preset table, does not define backlit behavior, and does not specify shutter-speed rounding. A production implementation should publish the exact preset names, stop offsets, source convention, and rounding rule.

• The Sunny 16 baseline is correct for full sun: f/16 at 1/ISO seconds, but the specification does not define the actual preset table or the stop adjustment for overcast, shade, and backlit conditions.
• For a requested aperture other than f/16, the required formula is not stated. Assuming an aperture value N and a lighting adjustment of s stops toward more exposure, shutter_seconds = (N/16)^2 × 2^s / ISO.
• The terms overcast, shade, and backlit are ambiguous without exact photographic definitions and fixed stop offsets; published Sunny 16 variants differ.
• The specification does not state whether the output is an exact calculated time or rounded to a standard shutter-speed setting such as 1/30 or 1/60.

Units and conventions

• ISO is treated as a dimensionless film/sensor speed index; 1/ISO is in seconds.
• Aperture input is the dimensionless f-number N, such as 16, 11, 8, or 32.
• Positive lighting-adjustment stops mean the scene is darker than full sun and require a proportionally longer shutter time.
• Shutter-speed outputs are calculated in seconds; reciprocal shutter notation is also reported for convenience.
• These vectors use the conventional Sunny 16 table: full sun = 0 stops, with no claim that this is the only valid published variant.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "lighting_condition": "full sun",
    "ISO": 100,
    "desired_aperture_f": 16
  },
  "expected_outputs": {
    "suggested_shutter_speed_seconds": 0.01,
    "suggested_shutter_speed_reciprocal": 100
  },
  "reference_data": {
    "sunny16_baseline": {
      "aperture_f": 16,
      "shutter_seconds_at_ISO_1": 1,
      "source_convention": "widely tabulated standard value"
    },
    "lighting_preset": {
      "name": "full sun",
      "adjustment_stops": 0,
      "source_convention": "widely tabulated standard value"
    }
  },
  "working": "Sunny 16 baseline: t = 1 / ISO = 1 / 100 = 0.01 s. Aperture correction: (16 / 16)^2 = 1. Therefore t = 0.01 × 1 × 2^0 = 0.01 s = 1/100 s."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The specification does not define validation behavior for ISO=0, which produces an undefined result, and it does not provide authoritative stop values or a sign convention for the backlit preset. A panel that accepts ISO=0 or silently chooses a backlit convention can return invalid or non-reproducible outputs.

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-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json