P3D Re: Hypo - Ortho - Hyper OR convergence angle?

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

>>>why pay all this attention to the terms Hypo, Hyper, and Ortho at all? 
>>Because they are derived from Greek roots?  :-)

Larry is replying to a message that I sent last night (and cc'ed Larry) but
has not appeared in P3d yet... I was trying to say that I find the terms
"hyper", "hypo" and "ortho" useful in giving me an idea about the subject
and tools used to record it.  Larry insists that it would be more useful to
give the convergence angle.  I think that if you want to go into details,
the interocular distance and the FL of the lenses should be recorded.

If you only give the convergence angle then only by knowing the size of
your object you can understand the situation involved.  Many tricks in
stereo photography are derived by playing games with the interocular
distance and size of objects (or lack of clue of size).

In the last expo folio there was a hypo (yes, HYPO) of a cat, taken with
the inner lenses of a Nimslo and close-up lenses.  Have you seen the movie
"Honey I shrunk the kids" and variations?  When seeing this picture I felt
like I was shrunk into a small size or the cat blew to a giant cat.  Both
cases could be recorded with the same convergence angle, yet knowing the
interocular distance is enough for me to understand the physical situation.

Similarly, in the case of hyperstereos, it is possible that a person cannot
tell the difference between a hyperstereo of a real scene or an ortho
stereo of a real model (same convergence in both cases).  Knowing that this
is a hyper gives the answer.

I have a picture of what looks like a wide bridge, wide enough to fit a
couple of cars.  In reality this is a very small passage over a highway
where two people could hardly fit together.  I used a 1/4 of the normal
interocular distance, hence the "illusion".

What good would be to know the convergence angle if there is no clue about
the size of the objects pictured?

I find the terms "hypo", "hyper" and "ortho" useful and sometimes I add the
terms "mild-hypo" and "mild-hyper".  Given the exact interocular distance
would be equivalent to using the exact focal length instead of the terms
"wide angle", "normal" and "telephoto" when describing lenses.

George Themelis


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