P3D re: world is non-ortho, reply

[Peter Abrahams <telscope@xxxxxxxxxx>]

George responded to my post of this evening:
>>I like a little hyper in my photos, increased sense of depth draws me into
>>the scene & 'makes me feel like I'm there'.  
>Just curious, what do you mean by "little hyper"?  Is the 6" of the
>side by side SLRs the little hyper you are looking for?

I use a Swanson Mk II twin P & S rig, Olympus lenses, 35mm f.l., 105mm
apart, and use a Red Button to view.  Anything but landscapes does seem a
little hyper to me, and I like it.

>>I also like to manipulate the placement of the photo in the window.
>You mean the placement of the window in the scene?

When I slide those chips back & forth, to me the window framed by the mount
seems fixed & the images move forward & back relative to it.  This might be
a less than standard use of 'window'. This is somewhat separate from ortho
reconstruction, but since convergence changes with this shifting, it is
related.

>>Those of you who spend lots of time at stereo photography might like a flat
>>scene to look flat in a photo, 
>It is not that we love it or strive to achieve it... but it happens from
>time to time...

Again, nobody has been saying that ortho is right all the time, but if
documentation or record-keeping is your goal, or for whatever reason you
want accurate reconstruction, a scene with little depth will give a slide
with little depth.  I was saying that for my purposes, anything to enhance
depth in such a shot is worth trying.

>>but if it looks as good in a flat shot, I'd
>>rather not go to the trouble of mounting, etc.  
>What trouble of mounting?  Didn't we agree that mounting is fun?
>Also, how would you know that the pair is flat if you don't mount it
>to look at it? 

I do enjoy mounting quite a bit.  But sharing stereo photography is a
constant challenge outside our clubs.  It does seem somewhat pointless to
me to have a stereo pair without depth, and such a shot seems less than
successful.  If it's part of a series, or a story line, then it serves a
purpose.
I use RBTs, and it only takes a short time to mount, and if they don't turn
out, the mounts are expensive enough that I'll re-use them.
And, just to be argumentative, in my experience, most stereos that turn out
flat can be anticipated when composing the shot.

>>But more than that, I'm an ortho-atheist.  
>By declearing yourself an ortho-atheist, you are recognizing that
>ortho is a religion.  Even John B. would not go that far...

Actually, my religion is to never use a smiley in communication, so
occasionally I get some unanticipated responses.  The discussions on these
lists have elicited quite a bit of discussion on orthostereoscopy, with
some participants assuming a role of advocacy.  

>>I like to keep orthostereoscopy
>>in mind without 'believing in it'.  One doesn't violate ortho for an
>>effect, it is violated because it is not inviolate.
>I cannot follow this... I violate ortho for an effect... it is called
>"hyper"

I meant, it's violated for good reasons, to enhance imaging, not as a
special effect.

>>For an individual stereoscopist, orthostereoscopy is possible.
>>However, once we start sharing our stereo photos, ortho is an average or
>>compromise.  There are significant differences between individuals in the
>>psychological & physical capacity of our natural stereoscopic equipment.
>Others have made the same point... which I find exaggerated.  You are
>talking about minor deviations... For example, there are RBT cameras with 
>75 mm lens' spacing and RBT cameras with 59 mm lens' spacing.  

I was referring to the dimensions & capacity of the human visual system,
not the camera's optics.  Ortho tries to reconstruct the scene as the
individual sees it, not as the camera sees it (now there's something we
could argue about).
I overstated my point, but the difference between an interpupillary
distance of 45mm and one of 80mm is significant, and the other variations
in human perception seem to me to be important as well.

>You are writing an essay for a show?  Are you going to read it?
>Any pictures going with it?

I'm not going to give a presentation, it's for explanatory text.  And it
doesn't have any of what I call humor.
I believe that my essays are like manure, of no value unless I spread them
around; so readers of this will get a chance to correct my mistakes again.
It should have pictures, but doesn't yet.  Sometimes those diagrams don't
make as much sense to me as a text does.  I'm going to try to put it all in
language, then go back & contrive some little triangles, arrows, schematic
eyeballs, and funny symbols like I see in the books.
_______________________________________
Peter Abrahams   telscope@xxxxxxxxxx
the history of the telescope, the microscope,
    and the prism binocular


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