Blethyn, Theodorus, 1675 c.
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Photo

photo - whole telescope
Basic Info

Maker: Blethyn, Theodorus

Year: 1675 c.

Year Range: -

Year Notes:

Manufacturing Location:

Signature: Theodorus / Blethyn / fecit

Signature Notes:

Stamped on main tub. Text 'fecit' is inverted.

Inscriptions:

Coat of arms

No stand present.

Collection: Optisches Museum

Accession #: 03/0180 1014

Sources:

Public Notes:

Maker known also in Louwman Collection (LC 35), but not listed in Webster Database.

Length (open):

Length (closed):

F-ratio:

Exit pupil:

Object status:

Optical Basics

Objective type: singlet

Optical style terrestrial

Physical style

Functional style

Materials: horn, pasteboard, vellum, wood, glass

Optical/Lab Data

Drawtube data:

Drawtube notes:

Boxwood stop on starside end of Draw 1 with aperture 15.5 mm (broken in half). Equally-spaced, 3-lens eyepiece insert in Draw 5. Insert has writing (printed English text, prob. form) on outside. Draw measurements: 217 mm (main tube), 101 mm (draw 1), 100 mm (draw 2), 105 mm (draw 3), 83 mm (draw 4), and 100 mm (draw 5).

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 23.80

Eyepieces

Notes: