T3D Re: T3D Convergence as a depth clue

["Lawrence A. Haines" <lhaines@xxxxxxxxxxxxxx>]

John:

Many years ago when several people were doing a lot of close-up work, I
remember Feeling like an ant looking at the pictures.  The objects
looked very large.  The stereo base was generally less than 65mm.

Larry Haines

John Bercovitz wrote:

> I was aware that if you had to cross your eyes to view a pair,
> the objects in the recreated scene looked smaller than normal
> because the excessive amount of convergence was not ignorable.
> I just did a closeup pair and mounted them in a standard mount
> with the far point set at the normal infinity separation and
> I find that the small objects look somewhat larger than life.
> It appears that viewing with far too little vergence can also
> be a depth clue.  I suppose this is not too surprising but I
> can't recall seeing it so clearly before.
>
> The objects were Chinese snuff bottles from the last century.
> They are small, under 50 mm in their greatest dimension.  The
> distance from camera to objects was under 300 mm and the
> stereobase was 67 mm.  The on-film deviation was well within
> normal (total depth in the scene was kept reasonably low) so
> the pairs are easily and comfortably viewed.  I used the Nikon
> 55 mm macro lens and of course it was racked out a ways to
> shoot this close.  I intended the pairs to be projected since
> around 70 mm operating focal length is good for projection.
> However, I viewed them with a 50 mm viewer since that was the
> closest match I had at hand.  So the objects are slightly
> flatter than they should be but it's not by an objectionable
> (easily noticed) amount.
>
> John B





------------------------------