The Spyglass

A telescope laid open on the bench. Watch parallel rays from a distant thing get gathered and re-aimed so it looks near — and inverted. Two instruments: a Keplerian refractor (two converging lenses) and a Newtonian reflector (a parabolic mirror, folded out the side). Drag the focal lengths; the magnification and every ray update live.

Instrument

Optics

Objective f _obj 600

Eyepiece f _eye 40

Aperture 120

Object tilt α 0.6°

Readout

View

Left = naked eye (1×) · Right = through the glass

Look

Angular magnification M = f_obj / f_eye. The Keplerian forms a real, inverted intermediate image at the shared focal plane, so the view is upside-down. The Newtonian's parabola focuses every parallel ray to one point — no spherical aberration. The self-test proves both to machine precision.