Telescope f-ratio

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Earth & Space

Tranche

tranche-2

Evidence ID

t2-041

Ledger rows

1

No ledger note is attached.

Review findings

The focal-ratio formula is correct under the stated unit and diameter assumptions. The instrument cannot receive an unconditional PASS because the claimed relative-speed output lacks a defined formula, and “speed” is not precisely labeled.

Formula and scope findings

• f/# = focal_length/aperture is the standard focal-ratio formula, provided aperture means aperture diameter and both lengths use the same units.
• The specification claims an output of relative speed vs f/10 but provides no formula for it. The standard exposure-speed ratio assumption is relative_speed_vs_f10 = (10 / f_ratio)^2; this must be explicitly adopted.
• The term “speed” is potentially ambiguous: the calculated quantity is relative exposure/light-gathering speed, not a directly measured physical speed.

Unit assumptions

• Focal length and aperture diameter must be expressed in identical linear units before division; the result is dimensionless.
• Aperture is the entrance-pupil diameter, not aperture radius.
• The f/10 reference is dimensionless and fixed at 10.
• Test-vector relative speed uses the standard inverse-square relationship: (10 / f_ratio)^2.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

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.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "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."
}

Related workflows

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche2/tranche2-results.json
• BOUNDARY_HAZARD_CATALOG.json