Tag Archives: church

Geometrical Optics and the Hastings-Byrne Refractor: Part II

Posted on April 1, 2012 by ST Editors

John Church Last month I reviewed the “lens-maker’s formula” that allows one to calculate the focal length (the inverse of the “power”) of a thin lens, provided that one knows the refractive index of the glass and the radii of … Continue reading →

Posted in April 2012 | Tagged , , , , | 1 Comment

Geometrical Optics and the Hastings-Byrne Refractor

Posted on March 6, 2012 by ST Editors

By John Church Some years ago I analyzed the objective lens of the AAAP’s historic 6-1/4-inch Hastings-Byrne (H-B) refractor and published the results in Sky & Telescope magazine, along with a history of the telescope1. The readers of Sidereal Times … Continue reading →

Posted in March 2012, Sidereal Times | Tagged , , , | Leave a comment