Keplerian telescope

Ray path in Keplerian telescopeclick for a larger image
Ray path in Keplerian telescope

Keplerian telescope

(kep-leer -ee-ăn) The first major improvement of the Galilean telescope, developed by the German astronomer and mathematician Johannes Kepler, in which a positive (convex) lens was used as the eyepiece in place of the negative (concave) lens that Galileo used (see illustration). This gave a larger though inverted field of view and much higher magnifications.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Keplerian telescope

[ke′plir·ē·ən ′tel·ə‚skōp]
(optics)
A telescope that forms a real intermediate image in the focal plane and can be used for introducing a reticle or a scale into the focal plane.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
All telescopic low vision aids are based upon two principal designs of distance telescopes: the Galilean, and the Keplerian telescope. The original telescopes were afocal, being designed to study the stars from which incident light reaching the telescope would have zero vergence.
In the Galilean system the exit pupil appears within, or internal to the telescope system and in the Keplerian telescope the exit pupil is external and virtual to the system, that is to say, it appears between the eye and the eyepiece (see Figure 4).
A rubberised eyepiece cup, present on the end of a Keplerian telescope, assists patients in locating the exit pupil as it allows the patient to rest the telescope within the orbit and closer to the eye.
Dutch scientist Christiaan Huygens discovers Saturn's rings and its moon Titan using a Keplerian telescope with an 11-foot focal length.