Re: John!!!

[P3D <PK6811S@xxxxxxxxxxxxxx>]

John addressing Bill:

>You're no doubt the one person on this list who best understands 
>the difference between your model and the "conventional" model.  
>Before anyone does these experiments, what would you say your model 
>will predict correctly and the conventional model will predict 
>incorrectly in these two proposed experiments?  I'm looking for
>what we will see; how we will know.

Well, I had a go at my experiment last night.  I won't comment
on the results because there are more variables to control than
originally expressed.  And John's question "how we will know" came
out as well.  Here's the setup I used:

  Camera   - Honeywell Spotmatic
  Lens     - Pentax 55mm (f1.9-f16)
  Subject  - White feather
  Lighting - 500 watt projector bulb, diffused through a white hankie
  Film     - Fuji Super HiG ASA-100 color negative

A stack of three extension tubes allowed me to bring the lens to about
one inch from the feather for a nice closeup.  I shot 16 pairs at
f1.9 and f16 on a roll of 36.  The feather was moved between pairs by
turning a screw 'just a twitch'.  The screw has 18 threads per inch
and was turned a grand total of 1/4 turn for approximately 1/4/18/15
= .0009 inch movement per twitch.  Pictures developed at a one-hour 
lab on 4x6 prints.

Got to try again because:

1.  diffusion was not sufficient, there are too many 3D shadow clues
2.  at f1.9 the lens is not sharp, nothing is really 'in focus'
    (you _can_ see depth but not much else :-)
3.  feather is a poor choice, I have seen too many closeups in
    both flat and 3D and have a strong mental model of the thing
    that interferes with my judgement.  

How do you know you are seeing depth???

A bit of dust on one side of a pair gives a clue, since it seems
to float above the fused image.  I placed a paperclip over
one side of the pair and tried to make myself believe it was
either laying on the surface of the feather or floating over it.

Another possibility is at the edge of the picture where the
feather should seem to 'fall away' as it curves back.

As for knowing whether one point is before or behind its neighbor,
some other subject would be a better choice, feather parts
are too orderly and predictable.  Maybe tearing a bit of tissue
would create a disorderly subject.

On the plus side:

The movement and magnification are about right for a flatter,
more disorderly subject.  I can see depth in all the pairs
for areas of the feather that curve away majorly, and in areas
that don't I can see depth on the two end pairs of the series.

There is one observation I have confidence in but will withhold
for the moment.  Let's just say it is score one for .... Allan!

(yeesh, gotta stop re-reading Bill's posts, I'm starting to withhold
information :-)

Paul Kline
pk6811s@xxxxxxxxxxxxxx


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