[ATM] Re: binocular views

[fabio at voreas.com (fabio@voreas.com)]

Another reason for objects to seem placed in layers is the fact that 
binoculars increase the effective eye separation, which changes depth 
perception. The interplay between increased magnification and increased eye 
separation is what causes the effect. 

Scientific American's Amateur Scientist (remember the good old days with 
hand-drawn black and white illustrations?) once featured two instruments 
(hyperscope and pseudoscope) that used mirrors to achieve some very strange 
effects. The pseudoscope would reverse what the eyes normally see, so that, 
believe it or not, farther away objects would tend to appear closer (I said 
"tend" because the brain would be screaming that it wouldn't be possible). 

Fabio
Redmond, WA 

Ross Sackett writes: 

>  
> 
> --- Charles Mitchard <charlesmitchard@iinet.net.au>
> wrote:
>> greetings all,
>> the other day I used a couple of pairs of standard
>> binoculars for
>> terrestrial viewing....
>> It looked like all the close trees were on different
>> layers at different 
>> distances, I found it quite interesting trying to
>> perceive the correct 
>> shape of the trees.
>> Is this a normal illusion in these instances?
> 
> Charles, 
> 
> Yep, that is normal: I see that all the time when I
> look at terrestrial views with even big binocs. Trees,
> buildings, etc., tend to look like flat stage scenery,
> arrayed in planes at different depths. 
> 
> Curiously, when I look at the moon in the sky with the
> same instruments it looks like a spherical ball,
> especially if there is some haze or whispy cirrus
> cloud intervening (for me this illusion of depth is
> weaker in crisp clear skies).  The odd part, of
> course, is that the parallax when viewing the trees is
> real and significant, but utterly negligible when
> looking at celestial objects like the moon.  Ain't
> neurology wonderful? Go figure. 
> 
> Ross 
> 
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