Telescope f-ratio implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t2-041

Effect

Computation or source lookup only

Input and validation requirements

The zero-aperture input produces an undefined f-ratio and should be rejected. The specification also leaves unit normalization unspecified, allowing a 1 m versus 100 mm input to be incorrectly computed as f/0.01 instead of f/10.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "focal_length": 100,
    "focal_length_unit": "mm",
    "aperture_diameter": 50,
    "aperture_unit": "mm"
  },
  "expected_outputs": {
    "f_ratio": 2,
    "relative_speed_vs_f10": 25
  },
  "working": "f_ratio = 100 mm / 50 mm = 2. relative_speed_vs_f10 = (10 / 2)^2 = 5^2 = 25."
}

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-tranche2/tranche2-results.json