Pinhole Concept

Demonstrations in Pinhole

Full setup: translucent screen at left, multicolor LED tower on stand at center, incandescent light bulb in wooden box at right, with bar clamp, lead brick, and masks on bench

Introducing a Pinhole

A sequential progression from shadow casting through slit projection to pinhole imaging. Students build intuition for rectilinear propagation, image inversion, and the pinhole camera principle by drawing ray diagrams at …
Screen showing dozens of inverted filament images projected through pinholes in aluminum foil, with the large lens visible at bottom
Safety

Pinhole Projection

Multiple pinholes in aluminum foil each project an independent inverted image of a lamp filament, demonstrating rectilinear propagation. A large converging lens then collects all pinhole images into a single …
Nikon DSLR camera body on green surface with a metal pinhole mount assembly attached and two interchangeable metal pinhole plates laid out beside it

Digital Pinhole Camera

Shows that images can form without lenses through geometric projection alone. Students observe the trade-off between aperture size, image sharpness, and brightness using interchangeable pinhole plates on a digital camera.
Two small pith balls suspended by fine threads from a bent metal rod, positioned between a lamp (left) and a projection screen showing filament-shaped shadow patterns
Safety

Negative Pinhole

Demonstrates the "negative pinhole" effect: small opaque objects cast shadows that transition from object-shaped to source-shaped as the object moves closer to the light. Students learn that rectilinear propagation allows …