Dioptrice : pre-1775 refracting telescopes

pre-1775 refracting telescopes

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Ramsden, Jesse, 1780 c.
Adler Planetarium and Astronomy Museum

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Basic Info

Maker: Ramsden, Jesse

Year: 1780 c.

Year Range: 1755-1800

Year Notes:

Manufacturing Location: London, England

Signature: Ramsden / London / Impd. Day or Night

Signature Notes:

Inscriptions:

No stand present.

Collection: Adler Planetarium and Astronomy Museum

Accession #: W-148

Sources:

Project investigation.

Public Notes:

The eyepiece is variable power. Main tube diameter 63 mm.

Length (open): 968

Length (closed): 336

F-ratio:

Exit pupil:

Object status:

Optical Basics

Objective type: doublet (crown forward)

Optical style

Physical style spyglass

Functional style

Materials: brass, glass, leather

Optical/Lab Data

Drawtube data:

Drawtube notes:

Objective Data

	C_A curvature (diopters):	C_B curvature (diopters):	P_D lens power (diopters):	f_D focal length (mm):	t thickness (mm):	free aperture (mm):	full aperture (mm):	nD refractive index:	ν Abbe No.:
Lens 1	7.70	-4.30	6.29	159.10	2.92			1.53
Lens 2	-5.36	2.04	-4.29	-233.00	1.35			1.58
Complete	2.03 ± 0.005	492.20 ± 1.1	4.32		38.50

Eyepieces

Notes:

Eyepiece 1

	f_D focal length (mm):	free aperture (mm):	full aperture (mm):	s spacing (mm):	C_A curvature (diopters):	C_B curvature (diopters):	M magnification:	FOV field of view (degrees):	Thickness:
Lens 1	80.90

Eyepiece 2

	f_D focal length (mm):	free aperture (mm):	full aperture (mm):	s spacing (mm):	C_A curvature (diopters):	C_B curvature (diopters):	M magnification:	FOV field of view (degrees):	Thickness:
Lens 1	156.90

Eyepiece 3

	f_D focal length (mm):	free aperture (mm):	full aperture (mm):	s spacing (mm):	C_A curvature (diopters):	C_B curvature (diopters):	M magnification:	FOV field of view (degrees):	Thickness:
Lens 1	87.20

Eyepiece 4

	f_D focal length (mm):	free aperture (mm):	full aperture (mm):	s spacing (mm):	C_A curvature (diopters):	C_B curvature (diopters):	M magnification:	FOV field of view (degrees):	Thickness:
Lens 1	49.00

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Dioptrice is made possible by the generous support of the National Science Foundation, the National Endowment for the Humanities, the Program in the History and Philosophy of Science at the University of Notre Dame, and the Adler Planetarium & Astronomy Museum.

+ Include in full text search:	Maker Manufacturing Location Description Signature Accession Public notes
+ Look for Blank Fields:	Maker Signature Year Manufacturing Location Inscriptions Provenance Drawtube Notes Public Notes Private Notes Objective Focal Length Eyepiece Focal Length Objective Notes Eyepiece Notes Magnification
+ Look for Non-Blank Fields:	Maker Signature Year Manufacturing Location Inscriptions Provenance Drawtube Notes Public Notes Private Notes Objective Focal Length Eyepiece Focal Length Objective Notes Eyepiece Notes Magnification
+ Year range:	1600 - 2014
+ Focal length range (mm):	0 - 2000
+ Free aperture range (mm):	0 - 2000
+ Full aperture range (mm):	1600 - 2014
+ Open length range (mm):	0 - 2000
+ Closed length range (mm):	0 - 2000
+ Categories:	Art Collection Book or Manuscript Instrument Collection
+ Materials:	organics bamboo black ivory bone boxwood ebony fish skin horn ivory lacquer leather lignum vitae mahogany paper parchment pasteboard rayskin shagreen sharkskin tortoiseshell vellum wood metal brass copper gilt gold leaf gold tooling iron platinum tooling silver silver tooling unknown glass glass rock crystal speculum other marble paint stone
+ Collection:
+ Objective type:	(all refractors) (all reflectors) (clear selection) N/A cassegrain doublet (crown forward) doublet (flint forward) doublet (unknown) gregorian herschelian newtonian singlet triplet unconfirmed unknown reflector

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Objective Data

Eyepieces