Hey folks, Not sure if this is the right group, but must be close...
I'm an amateur telescope guy, who years ago bought a binoviewer, (they
are, or are like, attaching a binocular set onto your telescope i.e.
let you see the object with two eyes, keeping the single objective.)
So, over the years, I have been become more convinced  -  that when
using a binoviewer', and comparing it with the image I saw with one
eye in the telescope, that the binovewer image is larger, both from a
subjective, 'in our minds eye' sense, and to any attempt at reasonably
measure it. (that I've come up with).
Further, well if you were to ask me, ;-)  it now seems arguable that
the idea can be more general - a binocular image, that is, using just
your eyes (i.e. no binoviewer) provides an increased field of view of
an object, than does a single eye view.

Now is that something anyone has any thoughts about or has heard of? -
be glad to hear about it.

Here's an experiment, to try and make a case, look at something out of
arms reach, Say a book a few feet away. With both eyes open, get an
idea of its horizontal extent (or angle across you view) by extending
your arms and using a finger to define the edges of the object. There
is a parallax and dual finger images to contend with in trying to do
it, but I think it is possible to fairly confidently represent the
width of the object by pointing with respective arms and fingers at
its edges. Resist the urge to, in a way, deconstruct your initial full
mental picture in trying to line up your fingers to the edges. Let the
object image dominate as you line up.

Now close one eye, for me what happens, is my fingers, one
particularly, now points quite a way beyond an edge. And the object
does look more remote and smaller. Or if I then, with one eye still
closed, align my fingers so that the one eye view represents the
angular size of the object, then open both eyes the object almost
transforms, extending beyond the bounds of my fingers.

Of coure there's the matter of arm and eye position parallax - but I
will initially try and diffuse that argument by saying, that since the
two eye images are an abstract of our brain, ie our brain has joined
two monocular views, and because therefore it is a menatlly abstracted
image (not raw visual data), despite also being an immediate, sensed
and conscious image, it can have an mental occupancy, or some such ...
a size perhaps, and therefore an apparent field of view, that truly is
larger than the single eye view.

A single eye telescopic view, seems to conform well to a particular
eyepieces stated field of view, say 50 - 80 degrees. But if you view
the same field (with a bino') with two of the same eyepieces
(binoculars will do) the apov grows.
It appears to me that this is a result of the image being 'sensed' or
mentally positioned with respect to our eyes and mind differently in
the two cases. With single eye the image appears to me as residing
behind that single eye and subtends whatever angle we may constrain it
to. With two eyes the image, with the same constraint (of viewed image
angle) on both eyes, provides an image which is bounded on both sides
by half the angle (i.e. outside bound for left eye is 25 degrees to
the left (in the case of 50 degree apfov and the right similarly) .

But now, the (mentally abstracted) binocular image seems to occupy a
greater extent of mental space, it fills my visual field, from one
side across to the other, and with the same image, as one eye. The
same image then fills, or is represented by a mental image which has
an extent bounded by the (half) angle to the outside of each eye.
Rather than with a single eye from just beyond my centre line to the
same outside bound. Since the mental image is formed at, or on, the
same plane as the single eye image, and the (half) angle from the
centre of our mental image, to the either outside bound, is greater,
so the binocular image now subtends a greater angle, the binocular
image is larger.

This is exactly the effect with a binoviewer, as if the image and
object have moved closer, become larger, it's as if I have been able
to sit and view from further into the bounded area. With a bino' the
difference is as if you are looking out a pipe one minute with one eye
to having your head half out a porthole with two eyes the next. So two
eyes make for bigger images.

Interestingly I can't see this effect on the vertical plane. Which
infers I'm stretching everything horizontally when I look with two
eyes, maybe I do.?? lol,.

Any thoughts/clarifications/especially rational dismissals would be
gratefully accepted. ;-)

Cheers,
S.