photo - whole telescope

Maker: Cunigham, Jacob

Year: 1661 c.

Year Range: -

Year Notes:

Manufacturing Location: Germany

Signature: Iacob Cunigham

Signature Notes:

Stamped on objective lens capstamped on objective lens capstamped on objective lens capstamped on objective lens cap

Inscriptions:

No stand present.

Collection: National Maritime Museum

Accession #: NAV1547

Sources:

Correspondence with curator (emails saved to file structure).

Schmitz, Emil-Heinz. Handbuch zur Geschichte der Optik. Bonn: J.P. Wayenborgh, 1981-1995. Erganzbd. 1, Das Fernrohr. [Image].

Royal Museums Greenwich. "Telescope".
http://collections.rmg.co.uk/collections/objects/43759.html.
[Accessed June 2016]

Public Notes:

Museum Description:
"This Galilean telescope has the name 'IACOB CUNIGHAM' and the date '1661' stamped onto the objective lens cap, making it one of the oldest dated telescopes in Britain. The two draw tubes are made of wood covered in marbled vellum, while the barrel and lens caps are made of wood covered in red leather with gold-tooled decoration. The eyepiece tube also has three gold-tooled stop lines identified by the German words 'NAHE', 'WEITH' and 'OVERSICHTIG'. These indicate different focusing lengths and suggest that the telescope was probably made in Germany. Jacob Cunigham may have been either the maker or the original owner of the telescope. The larger draw tube also has a single gold-tooled stop line. The curious shape of the barrel is designed to accommodate a large objective glass. At this time it was easier to grind a large lens than a small one. Brass diaphragms over the end of each lens have been used to reduce their apertures" (Royal Museums Greenwich).

PROJECT NOTES 2016:
First impression: Lenses look original
Very different colors
Greenish hue to objective
Ocular has large area of matte finish, with deep central well

Brass objective diaphragm outer diameter 79.44 mm, inner diameter is 39 - 40 mm. Thickness ranges from 0.49 to 0.64 mm

Brass ocular diaphragm is stopped from 47.6 mm down to 18.0 mm. Thickness ranges from 0.15 - 0.21 mm.

Brass looks very different. A lot of texture on the objective, but plain on the ocular.

Split brass rings
Objective thickness: 2.5 mm
Ocular thickness: 2.1 mm

Objective:
-thickness
- 3.4 mm (at edge)
- 5.1 mm (in middle)
Objective is biconvex, one side more plano.

Both lenses are polished but not smooth

Telescope f ratio (F obj / obj aperture): 18.4

Eyepiece Unit Notes 2016:
Eyepiece has large matte surface, with deep central well, typical of early Galilean telescopes. Brass ocular diaphragm thickness ranges from .15mm to .21 mm, again suggesting it is original. Diaphragm has outer diameter of 47.6, stopped down to 18.0 mm.

Provenance:

Caird Collection

Length (open): 688

Length (closed): 325

F-ratio: 18.45

Exit pupil: 0.0

Object status:

Objective type: singlet

Optical style galilean

Physical style spyglass

Functional style

Materials: wood, gold tooling, glass, brass, vellum

Drawtube data:

physical lengths in mm:
starside to extension mark:
star-side tube diameter:
eye-side tube diameter:
ring diameter:

Drawtube notes:

Extensions of tubes are marked with pins; each mark is accompanied by a pin that appears to do nothing else. Interior stops are made of brass. Tubes are made of wood covered with leather. Draws are covered with combed marbled paper. Each draw is wood, all the way through, made of a single piece of [apple?] wood, turned on a lathe. Tubes are snug, with leather fitting tightly on the wooden firmament.

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	491.57	1835.58	1.37	725.00	5.10	39.30	77.90
Lens 1 notes: Direct focal length measurement results from illumination of entire lens rather than stopped down via diaphragm. Lenses look original. Objective and eyepiece have very different color, with a greenish hue to the objective. Brass objective diaphragm has outer diameter of 79.4 mm, inner diameter of 39 - 40 mm. Diaphragm thickness ranges from .49 to .64 mm, indicating it is likely original. Brass looks very different on the two diaphragms, with lots of texture on objective, and plain on ocular. Split brass ring holds each lens in place: objective ring is 2.5mm thick, ocular ring 2.1 mm. Objective thickness ranges from 5.1 mm in middle to 3.4 mm at edge. Both lenses are polished but not smooth. Objective is biconvex, with one side nearly plano. Ronchi test of entire lens shows it is well-made. Data are reliable
Lens 2
Lens 3

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		10.00	42.90		12349.66	-41.44

Wavelength	Paraxial	70%	Whole
652	±	-1.06 ± 0.11	±
575	±	0 ±	±
482	±	3.36 ± 0.03	±