Source: https://guthlabs.ai/docs/instruments/telescope-field-of-view/mechanism/

instrument mechanism / verified-clean

# Telescope Field of View mechanism

The inspectable method record for Telescope Field of View, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The stated honest label appropriately identifies this as an approximation, but the user-facing name or output should say approximate true field of view unless field-stop and distortion corrections are implemented.

- AFOV/M is the standard nominal approximation, not an exact true-field formula; actual field of view depends on the eyepiece field stop and optical distortion.

- The phrase "magnification (or focal lengths)" is ambiguous because it does not explicitly identify telescope and eyepiece focal lengths or state that M = telescope focal length / eyepiece focal length.

## Units and conventions

- AFOV is expressed in degrees.

- Magnification M is dimensionless and must be positive.

- If focal lengths are supplied, telescope and eyepiece focal lengths must use the same units; M = F_telescope / F_eyepiece.

- Convert degrees to arcminutes with 1 degree = 60 arcminutes.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "eyepiece_AFOV_deg": 50,
    "magnification": 100
  },
  "expected_outputs": {
    "true_FOV_deg": 0.5,
    "true_FOV_arcmin": 30
  },
  "working": "TFOV = AFOV / M = 50 / 100 = 0.5 degrees. Arcminutes = 0.5 × 60 = 30 arcminutes."
}
````

## Failure boundary

- Division by zero occurs when magnification is zero.

- Zero or negative magnification is physically invalid and should be rejected; focal lengths must be positive.

- The approximation can be inaccurate for eyepieces with significant angular distortion or when the field stop limits the view.

- Very large AFOV-to-magnification results may exceed the physically usable field of the telescope or eyepiece.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche3/tranche3-results.json`