Reciprocity Failure Calculator (Film) mechanism

Model scope

The stated formula can be used as a rough, explicitly seconds-based approximation, but the specification is not sufficient to verify stock presets or claim general accuracy. The honest label should say that results are approximate fits valid only over named manufacturer-documented exposure ranges, and should warn that unusual, aged, expired, cold-stored, or differently processed stocks may require manufacturer correction curves. No universally famous film reciprocity exponent exists; the exact reference entries used here are standard SI time values rather than claimed manufacturer exponent values.

• correctedTime=meteredTime^p is only an approximate Schwarzschild-style model, not a universal reciprocity-failure formula for all film stocks; manufacturer correction curves or stock-specific fitted equations are preferred.
• The formula is dimensionally and numerically unit-dependent unless meteredTime is explicitly normalized to a reference unit, conventionally 1 second. For example, applying p=1.5 to 1 minute numerically gives 1 minute, whereas converting first to 60 seconds gives 464.758 seconds.
• The specification does not define the valid exposure-time range for each exponent. Reciprocity behavior is often piecewise and may differ below approximately 1 second, at very long exposures, with different developers, temperatures, filtration, or processing conditions.
• The lookup table is underspecified: no actual film-stock names, manufacturer datasheet editions, exponent values, fit ranges, or uncertainty values are supplied.
• The allowed domain and validation rules for meteredTime and p are missing. Negative times are invalid, p should normally be positive, and zero exposure is not a physically meaningful photographic exposure even though the arithmetic can return zero.

Units and conventions

• All worked calculations use meteredTime in seconds and return corrected exposure time in seconds.
• The exponent p is treated as dimensionless and as a manually supplied model parameter; any preset p must be tied to a named film stock, manufacturer datasheet, fit method, and validity range.
• The formula is interpreted as correctedTime_s=(meteredTime_s)^p, equivalent to using a 1-second reference time; a production implementation should expose or document this normalization explicitly.
• The exact SI time-table values used below are 1 s=1 s and 1 min=60 s.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "metered_time": 1,
    "time_unit": "s",
    "exponent_p": 1.3,
    "film_stock": "manual exponent"
  },
  "expected_outputs": {
    "corrected_time_s": 1
  },
  "reference_data": {
    "time_reference_s": 1,
    "source_convention": "widely tabulated standard value (SI): one second equals one second",
    "exponent_p": 1.3,
    "source_convention_exponent": "user-supplied manual exponent; not a manufacturer table value"
  },
  "working": "correctedTime = meteredTime^p\n= 1^1.3\n= 1 s.\nThis is an exact boundary case and lands on the widely memorized 1-second SI time entry."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The calculator must reject negative metered times when using a fractional exponent such as 1.3 because the real-valued result is undefined. It also has a significant unit-convention hazard: applying the power to an unnormalized numeric time makes seconds and minutes produce different physical results.

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