photo - whole telescope

Maker: Unknown

Year: 1617 c.

Year Range: -

Year Notes:

Manufacturing Location:

Signature:

Signature Notes:

Inscriptions:

No stand present.

Collection: Kunstgewerbemuseum / Staatliche Museen zu Berlin

Accession #: P19

Sources:

Project investigation.

Bolt, Marvin, and Michael Korey. "The world's oldest telescopes," in THE ORIGINS OF THE TELESCOPE (Amsterdam 2010), p. 235-7.

Riekher, Fernrohre (1990), 47. We thank Rolf Riekher for sharing with us with his insights and meticulous optical measurements, as well as for many stimulating conversations.

Public Notes:

Made 1617 or prior by an unknown maker in Augsburg, Germany, part of the Pommerscher Kunstschrank.

Main tube and five draws constructed of pasteboard. Each draw covered in marbled paper; end tube and ring stops in silk velvet embroidered by gold thread. Collapsed, rings and end tube form cylinder with common outer diameter (48 mm), common feature of other early scopes.

The cabinet that contained this telescope included documentation of the various artisans involved in assembling the Kunstschrank. This documentation makes this instrument the world's oldest surviving, securely-datable telescope (see Hainhofer's inventory of the cabinet).

Objective Notes:
Lens is plano-convex with grozed edge. Full aperture 38.4-41.4 mm. Free aperture 16.3-17.4 mm. Velvet aperture of the objective: 41.4 (full) and 16.9 (free). Lens is possibly devitrifying or crizzling. When the telescope tubes are extended to extension marks. the lens separation measures 900 mm. Distant objects are in focus at that separation. Objective focal length of about 960 mm implies an ocular focal length of 60 mm, and a magnification of 16. Lots of bubbles in the lens. Color of objective is slightly yellow, whereas ocular showed a distinct bluish or grayish tint.

Field of view is only about 4 m at a distance of 1000 m, or under 15 arc minutes, for an eye pupil opening of 6 mm, but it gives a surprisingly clear and sharp (upright) image (Riekher, 1990).

Eyepiece Notes:
Lens is plano-concave with grozed edge. Full aperture: 22.9-23.8 mm. Central well: 19.6 mm. Thickness: 2.2 mm.

Provenance:

From the Pommerscher Kunstschrank.

Length (open): 923

Length (closed):

F-ratio:

Exit pupil:

Object status:

Objective type: singlet

Optical style galilean

Physical style

Functional style

Materials: pasteboard, paper

Drawtube data:

Drawtube notes:

Tube measurements: Main tube is 202 mm, draw 1 is 135 mm, draw 2 is 142 mm, draw 3 is 145 mm, draw 4 is 145 mm, and draw 5 is 154 mm.

Objective Data

	CA curvature (diopters):	CB curvature (diopters):	PD lens power (diopters):	fD focal length (mm):	t thickness (mm):	free aperture (mm):	full aperture (mm):	nD refractive index:	ν Abbe No.:
Lens 1		495.69		960.00	2.50	40.00	17.00

Eyepieces

Notes:

Eyepiece 1

	fD focal length (mm):	free aperture (mm):	full aperture (mm):	s spacing (mm):	CA curvature (diopters):	CB curvature (diopters):	M magnification:	FOV field of view (degrees):	Thickness:
Lens 1	60.00		23.35 ± 0.45		29.18	24555.24	16.00