Marine Monocular Keplerian Telescope
This antique marine monocular Keplerian telescope is a classic example of the nautical optical instruments that guided sailors across the world’s oceans. It extends fully to 60 cm and collapses to a compact 22 cm for easy stowage. The brass construction is characteristic of the finest marine telescopes produced for professional and naval use.
Keplerian Optics Explained
The Keplerian telescope design takes its name from Johannes Kepler, who described the principle in 1611. It uses a convex objective lens and a convex eyepiece lens. This configuration produces an inverted image but delivers superior magnification and a wider field of view than earlier Galilean designs. At sea, where scanning a distant horizon demands optical power and clarity, the Keplerian design proved indispensable.
Built for the Sea
Marine telescopes demanded rugged, reliable construction. Brass was the material of choice for centuries of instrument making. It resists corrosion from salt air and seawater exposure. It machines to tight tolerances, ensuring smooth draw-tube action. This telescope’s multi-draw barrel extends and collapses with the precision expected of a working nautical instrument. Every element reflects a design philosophy built around performance at sea.
A Long History of Naval Use
The monocular marine telescope became standard equipment aboard naval and merchant vessels from the 17th century onward. Officers used them to identify distant ships, read signal flags, and navigate coastlines. The collapsible multi-draw format made them practical for use from a ship’s deck, where space and weather demanded compact, durable tools. Examples like this one bridge the worlds of scientific instrument making and maritime history. Read the history of the Keplerian telescope at the Museum of the History of Science Oxford
Dimensions and Condition
This telescope extends to 60 cm and collapses to 22 cm. The brass barrel shows the honest patina of age and use. The draw tubes operate smoothly. It represents a fine museum-quality example of the marine monocular Keplerian telescope form at its most functional and enduring.
See our antique telescopes and binoculars museum collection.
