Over-under binoculars
BACK IN OUR AUG/SEP 2019 ISSUE,
I wrote about Frank Szczepanski’s unique approach to making a binocular telescope using only four mirrors instead of the traditional six. Frank has since reduced the number of mirrors required to two.
Of course, that requires a set of objective lenses up front instead of primary mirrors in back, but there’s plenty of innovation in between.
One of the biggest problems with any large binocular telescope is that the distance between the centres of the primary light-gathering elements — be they mirrors or lenses — is wider than the spacing between the observer’s eyes That means the light must be bounced off matching sets of mirrors to bring the optical axes closer together.
