Ramsden, Jesse, 1780 c.
Adler Planetarium and Astronomy Museum Arrow right Arrow left
Photo

diagram
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

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 7.70 -4.29 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
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 80.90
Eyepiece 2
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 1 156.90
Eyepiece 3
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 87.20
Eyepiece 4
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 49.00