Equations · equation
Thin Lens Equation
Waves & Optics · 1693
- Equation
- 1/f = 1/d_o + 1/d_i
- Field
- Waves & Optics
- Symbols
- f focal length · d_o distance from lens to object · d_i distance from lens to image
- Year
- 1693
Significance
Where a lens puts the image of an object, given how strongly it bends light. Halley wrote it in 1693, though the ray tracing goes back to Kepler. It sizes a camera, a telescope's eyepiece, a pair of spectacles and the analyzer's photograph; the same form serves a curved mirror.
Referenced by
equation
instrument
Open on the Equations shelf — the interactive card, the filters, and everything alongside it.