10x50 finder with cross-hairs


These finders are made of each a half of a 10 Euro eBay binocular. The binoculars itself were trash, as the mechanics did not allow a stable collimation of both sides any more, which does not bother if you use only a single half of it. Most parts, except for the prism bearings are made of plastic, such that these finders are lightweight, despite of the Porro prisms.

Both sides of the field glass were separated by a saw from the central focusing bar and the eyepiece sleeves were glued to the bodies by epoxy at a fixed position. The eyepieces itself can still be unscrewed from the bodies. One of the finders can be focused by the built in focusing adjustment, the other one by turning the  eyepiece in its thread.

The crosshairs are made of two hairs (hence the name!), glued to a cardboard ring, that exactly fitted on the field stop of the eyepiece without vignetting.


Compared to standard 30 mm finders, this 10x50 finder is a considerable step forward. Under dark skies many Messier objects are visible already in the finder. Moreover, the finder delivers an upright image of the sky (as a field glass does). The view in the finder has therefore the same orientation as the direct view of the sky.