# Slide projector

> A bright slide beyond the focal length — one lens throws an inverted picture onto the screen.

![Slide projector](https://www.loomrume.com/optics/stills/slide-projector.png)

**Christiaan Huygens** · c. 1659 — Huygens’s magic lantern

Huygens sketched a lantern that threw painted slides on a wall and then half-disowned it as a toy for scaring people. Kircher printed a similar box. The photographic slide projector of the nineteenth century is the same conjugate: object outside the focal length, real inverted image on a screen.

One convex lens is enough for the idea. This bench leaves the “slide” as a luminous object and lets you slide the lens until the screen sharpens.

## Sources

- [Magic lantern](https://en.wikipedia.org/wiki/Magic_lantern)
- [Christiaan Huygens](https://en.wikipedia.org/wiki/Christiaan_Huygens)

## Links

- [HTML](https://www.loomrume.com/examples/slide-projector)
- [Open in Studio](https://www.loomrume.com/experiments/new?template=slide-projector)
- [llms.txt](https://www.loomrume.com/llms.txt)