It occurs to me that a Mirscope, being a non-distorting viewing system,
could test the limits of eye convergence. What would happen if you placed
the apparent window at a distance of 18 inches? Could an average pair of
eyes converge on an object at that distance and then diverge out to
parallel viewing in the same view? Conversely, how common is it that
someone is simply unable to view stereo through a Mirscope?

Oleg Vorobyoff

--- In MF3D-group@yahoogroups.com, Oleg Vorobyoff wrote:

>
> It occurs to me that a Mirscope, being a non-distorting viewing

system, could test the limits of eye convergence. What would happen
if you placed the apparent window at a distance of 18 inches? Could
an average pair of eyes converge on an object at that distance and
then diverge out to parallel viewing in the same view? Conversely,
how common is it that someone is simply unable to view stereo through
a Mirscope?

Hi Oleg,

In my experience, having used the rig at open-houses, art-galleries,
and other public venues, where few, if any, people are experts at
stereo, essentially 100% of viewers get it right away. Only one
person, wearing seamless bifocals with all sorts of corrections,
claimed problems. But that person probably would have had trouble
viewing ordinary photographic prints or paintings through such
optics. Don Lopp, wearing somewhat similar glasses, said it was fine
for him.

As for your thought experiment, wouldn't that create a huge effective
deviation between the images. When I converge on a finger 18" away,
I can't come near to resolving things at infinity concurrently.

John
www.mirscope.com

John Hart wrote:

>
>As for your thought experiment, wouldn't that create a huge effective
>deviation between the images. When I converge on a finger 18" away,
>I can't come near to resolving things at infinity concurrently.
>

Seems like the natural way our eyes work. Is that a problem?


Chuck





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John Hart wrote:

>As for your thought experiment, wouldn't that create a huge effective
>deviation between the images. When I converge on a finger 18" away,
>I can't come near to resolving things at infinity concurrently.

Sounds natural to me, is that a problem?

Chuck






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Chuck Holzner wrote: >

John Hart wrote: >>

>>As for your thought experiment, wouldn't that create a huge effective
>>deviation between the images. When I converge on a finger 18" away,
>>I can't come near to resolving things at infinity concurrently.

> Seems like the natural way our eyes work. Is that a problem?

The natural way our eyes work is for them to auto-focus on one separate
object at a time. Such as at infinity, or at something closer, but
not both at the same time. The eye can only focus on an object, in
an angle of about one degree. The finger at 18 inches, will encompas
an angle of more than one degree.

(The operational word, was, "concurrently", ("occurring at the same time").

The deviation of the eyes will be about 3.1mm.


Best regards,

DON

Chuck Holzner >
John Hart wrote >>

>> As for your thought experiment, wouldn't that create a huge effective
>> deviation between the images. When I converge on a finger 18" away,
>> I can't come near to resolving things at infinity concurrently.

> Seems like the natural way our eyes work. Is that a problem?

The operational word is, "concurrent". I do not believe that John H.
is the only one that can not look at a finger which is only 18 inches
away, and at the same time see infinity. I can not do it. The
deviation is, approximately, more than 3.1mm

Incidentally, I do not believe that our eyes have near enough depth of
field to be able to perform such a feat.


Best regards,

DON

Don wrote:

> The operational word is, "concurrent". I do not believe that John H. is the only one that can not look at a finger which is only 18 inches away, and at the same time see infinity. I can not do it. The deviation is, approximately, more than 3.1mm

Chuck:

The idea is to make the view look the same (or better) than it did while viewing the scene directly. Since one can not focus his attention on a finger at 18" and infinity at the same time viewing direct, it should be at least OK if he couldn't do it while viewing a slide.


Don:

>Incidentally, I do not believe that our eyes have near enough depth of field to be able to perform such a feat.

Chuck:

Having more depth of field in the slide than in your eye, to me, would be a plus. I could move my eyes from subject to subject without having to refocus (Tilt my head up or down with my glasses on) and it would be more enjoyable then direct viewing. With outdoor light (sunny 16) I find that my eyes stop down and give me good focus from arms length to infinity without glasses even though my old eyes focus at or beyond infinity. I have never noticed that having better focus on anything was a problem. Sharpness in a picture does not hurt my eyes.

I really don't believe that you can get good DoF from 18" to infinity with a MF stereo camera, at least not with any I have seen, so such a picture is not likely. My TEST picture of the Pitcher Plant was done to show that DoF plays out before OFD becomes a problem. Using F/22, I focused the Sputnik all the way in (about 1 meter or so,) and photographed from a low tripod so that I had plants in at 18 inches, the Pitcher Plant at one meter and the background way out (infinity). I had to make my own mount so as to be able to have infinity at zero parallax and not have window violations.

No one has told me that they can not converge on anything in the view but they do complain about things being out of focus even though the Pitcher Plant is sharp while extreme near and far are not. (Maybe they are just being nice.) No doubt someone with an adjustable inter-ocular viewer could adjust the inter-ocular to where a 65mm infinity spacing would create a painful toe-out of the eyes but I use my Saturn.

I find that adjusting my Sputnik to F/32 and focusing at twice the distance to the nearest object, I can get acceptable DoF from 5 feet to infinity resulting in 3mm OFD. With 3mm OFD I can mount in commercial mounts that have 62 mm aperture spacing using an infinity spacing of 65mm and keep everything behind the window with no eye divergence or strain. I can mount even more OFD by modifying the mount (or through the window) but then DoF starts becoming a problem. I would not buy a MF stereo camera that can not do, or can not be easily made to do, F/32 or tighter.

Regards,

Chuck






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John Hart wrote:

>...essentially 100% of viewers get it right away.

That is very encouraging. Sounds like the Mirscope is easier on the eyes
than lens based viewers.

>As for your thought experiment, wouldn't that create a
>huge effective deviation between the images.

Yes. I am wondering what are the limits of fixed focus stereo viewing -
whether eventually the distance at which the eyes are converged becomes so
different from the distance at which they are focused that viewing a stereo
pair becomes uncomfortable. In normal vision one has no difficulty in
switching the eyes from an object 18 inches away to something in the far
distance. But if your focus were tied down at 18 inches, how much could
you comfortably diverge your eyes? All the way to parallel?

Come to think of it, when freeviewing, or viewing one of those magic eye
stereograms, you ARE asked to focus at reading distance and view with eyes
parallel. Most people cannot do that without a lot of training. So my
question becomes, would this feat be easier in the less confusing optical
environment of a Mirscope?

Oleg

--- In MF3D-group@yahoogroups.com, "Chuck Holzner" wrote:

>
> John Hart wrote:
> >
> >As for your thought experiment, wouldn't that create a huge

effective deviation between the images. When I converge on a finger
18" away, I can't come near to resolving things at infinity
concurrently.

>
> Seems like the natural way our eyes work. Is that a problem?
>
>
> Chuck

Yes, exactly. No problem. But to expect a viewing system to circumvent
this (was that what Oleg was asking for?) fact of nature seems a bit
much.

John