# Keplerian telescope

> Two convex lenses with a focus between them — brighter magnification, but the image is upside-down.

![Keplerian telescope](https://www.loomrume.com/optics/stills/keplerian-telescope.png)

**Johannes Kepler** · 1611 — Dioptrice

Kepler wrote the two-convex recipe in Dioptrice and did not build one. Scheiner and others did, a few years on. A real image sits between the lenses, so you can put a reticle there; the view is upside down; the field is wider than [Galileo’s](https://www.loomrume.com/examples/galilean-telescope.md).

Almost every astronomical refractor after that is this tube with extras. On the board: two convex glasses, focus in the gap, parallel in and out, inverted.

## Sources

- [Keplerian telescope](https://en.wikipedia.org/wiki/Keplerian_telescope)
- [Johannes Kepler](https://en.wikipedia.org/wiki/Johannes_Kepler)

## Links

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