BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="elkcub" data-source="post: 3193170" data-attributes="member: 14473">Omid,Perhaps a word is in order here.  The only binoculars anyone has seen, or will see, with diverging telescope tubes is out of alignment.  The reason binoculars aren't designed that way is not because it can't be done, but because humans can't use them.  It's inconsistent with their oculomotor systems.  The first attachment is from "Visual Instrumentation: Optical Design and Engineering Principles," by Pantazis Mouroulis (1999).  When he says: "The eye can tolerate only a small amount of divergence, something in the order of 0.5˚usually being acceptable," he means the eyes can usually be that divergent before diplopia (double vision) sets in or the brain turns off one image and visualizes monocularly.  Clearly, this is not the way to get greater FOV.  I realize that you're pondering the design limits of binoculars in relation to how the eyes work, so the best source book I can recommend is: "Oculomotor Systems and Perception," by Sheldon Ebenholtz (2001).  It's really worth reading.  Unfortunately, what you (and several others) don't yet understand is that stereo vision only results when spatial image points fall on "corresponding" parts of the retinae.  The locus of such point in space, called the visual horopter, determines how the brain fuses the two images.  The collection of points off the horopter are unconsciously suppressed double images.  However, if no points in space define a horopter, (which would be the case for diverging telescopes) the entire scene will be seen as a double image (i.e., diplopia).  Again, the Ebenholtz book provides the greatest insight for the least time an effort.  This process of binocular vision is quite amazing, but it also determines the useful limits of instrument construction.  The second attachment is from the Ebenholtz book, but he obtained the chart from much earlier publications.  I guess this is also a good place to point out that the Pentax Papilio does, in fact, converge the telescope views as a function of distance (third attachment).  This capability is consistent with Mouroulis' comments (first attachment) with regard to normal oculomotor convergence.  Ed</blockquote>

Verification