Image of the day

From the
ATWB Customer Gallery

KOFA Wildlife Refuge, Arizona

My Account

New to Astromart?

Register an account...

Need Help?

bino-periscope/rabbit ears variation

Started by yahganlang, 09/19/2005 08:19PM
Posted 09/19/2005 08:19PM Opening Post
For my 6" bino project, I've been trying to figure out how best to fold the refractor paths. One idea that occurred to me today was to have the main tubes end-to-end, perpendicular to the facing direction of the viewer, like old fashioned military "rabbit ears" stereo range-finding binos when maximally unfolded. Large first surface mirrors would be mounted directly behind the objectives, giving a periscope effect.

Configured this way, most of the weight of the tubes could be much more distributed along the pivoting axis bar for altitude, end ep height would vary little. Admittedly this bar could be a bit unwieldy, as it would be almost twice the focal length. Anyway, I'd like comments about feasibility, or prior successes and failures of such a design if anyone has heard of them. Thanks.

Jess Tauber
Posted 09/20/2005 08:44AM #1

Your way would require large, very high quality flats. Maybe a compromise: fold the path halfway back, which would require 3 inch flats (or even 1/3 of the way, for 4 inch flats). You would still have some of the advantages: most of the weight being distributed along the altitude axis, and reduced EP motion. But it would give you much less total weight, much less cost, and probably better optical performance (1/20th wave 3 inch elliptical secondaries are easy to find...very difficult at 6 inches). HTH,

Tim Iafolla