P3D Focus and Depth

["OLE HANSEN" <olejohan@xxxxxxxxxx>]

Andrea Blair asks:
> Can an image be sharp (in respect of DOF) and still be *flat* ?
Yes - if it is a 2D image.

> Does DOF automatically produce the perception of depth in stereo?
No - stereopsis has nothing to do with depth of field.

> If so, is an extremely sharp but completely flat stereo image
> better/worse/different than a selective focus image that shows depth?
A "flat" image is not a stereo image.

> If you (anyone) had to choose, what would be your preference?
Stereograms.

> Any thoughts?
Good question !


Eric Goldstein <egoldste@xxxxxx> wrote:
> Andrea asks some interesting questions....
I disagree - these questions are not interesting - not even provoking.

> the relationship between focus and the perception of depth if one
> exists....
It does indeed - read any tekstbook on stereophotography.

> but anyone who really knows what they are talking about should jump
in....
So being invited - read Ferwerda, Piper, Holmes, Wheatstone, Brewster....

> First, I'd just point out that flat pix are only flat in relation to a
> stereo pair. They contain all the depth cues which stereo pairs contain,
> save one: parallax.
A rather important point, when the topic is stereophotography.

> One eyed people perceive depth, and "one eyed pictures" normally have
> plenty of depth information within them...
There is no depth in 2 d pictures. You mix up perspective and stereopsis,
a quiet common mistake.

> These are no more illusional nor are they less "real" than the
> reconstruction of depth via parallax.
Do you have two working eyes ?

> Some of us stereophiles (stereosexuals?) may regard the reconstruction
> of depth via parallax as a more striking with greater impact but that
> is purely subjective...
Your turning stereopsis into a perversion is just to much !

> how flat is flat....
Flat !

> how sharp is sharp....
That depends on camera and film.

> distant mountains seldom if ever look "flat,"....
They allways look flat, but you prefer obviously to believe that they are
not, and selfdeception is a negative habit, when used in scientific or
missionary activities.

> a selective focus image that shows depth and my answer is that is
> it irrelevant to me !
That is your way of looking at the problem, but why do you then
take an interest in stereophotography ?

> I am a creative director by trade and so commission all manner of
> still, film, video, etc, and am oriented toward whether an image
> is successful or unsuccessful rather than good or bad.
I am impressed by your status as director, but not of your nowledge.

> Often the greatest surprise for me as a creative director, teacher
> and judge is when someone presents a piece which provides an
> extraordinary view of an ordinary subject and so provides a delightful
> visual surprise/exploration.
You do get quite a few of those surprises, dont you ?

> We are, after all, all colleagues in our pursuite of improved skills
> and teachers to each other in this endeavor....
I doubt that - You do not seem to have the chance to improve your skills
as you now all the answers as a creative director, teacher and judge.

> and I greatly appreciate the patience and respect shown by listmembers
> to by screwball ideas though they may not agree with them, and encourage
> each of us to return that patience and respect in kind.
You have brought my patience and respect to an end by your posting.
regards - Ole Hansen - olejohan@xxxxxxxxxx


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