{"id": "card_opt_lenses", "kind": "reference", "title": "Lenses — focusing by the thin-lens equation", "body": "A lens focuses by 1/f = 1/do + 1/di (image at 15 cm for the sealed example); magnification is the ratio of distances. Every camera, eye and telescope is this geometry of rays. Rests on Maxwell.", "source": {"label": "Narrow Highway — optics", "url": "", "authority_tier": "engine_derived"}, "shelf": "codex", "box": "optics", "bands": ["optics", "pillar", "lenses", "one map"], "subject": "Lenses — focusing by the thin-lens equation", "connections": [{"to_card_id": "card_floor_optics", "relationship": "part_of", "evidence": "a pillar of optics (Lenses)"}, {"to_card_id": "card_floor_maxwells_equations", "relationship": "connects_at", "evidence": "ray optics is the short-wavelength limit of Maxwell's light"}], "author": "engine", "created_at": 0.0, "updated_at": 0.0, "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "generated": false, "call": "codex.optics", "facets": {"subject": ["lenses", "one map", "pillar"]}, "presentation": {"glyph": "•", "kind_label": "optics", "by": "Narrow Highway — optics", "authority": "engine_derived", "posted": "", "standing": ""}, "neighbors": [{"id": "card_floor_optics", "title": "Optics — how light bends, focuses, and slows", "relationship": "part of", "why": "a pillar of optics (Lenses)", "href": "/card/card_floor_optics", "resolved": true}, {"id": "card_floor_maxwells_equations", "title": "Maxwell's equations — the first unification", "relationship": "connects at", "why": "ray optics is the short-wavelength limit of Maxwell's light", "href": "/card/card_floor_maxwells_equations", "resolved": true}], "house": {"door": "FIND", "kind": "card", "trail": "connections", "seal": "/card/card_opt_lenses", "next_step": {"do": "follow a connection: what this card rests on, and what rests on it", "door": "FIND", "tool": "card_connections", "params": {"id": "card_opt_lenses"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}