T3D Re: Panum's limit

[Peter Homer <P.J.Homer@xxxxxxxxxxxxx>]

 John Bercovitz replied to my post.

>>I haven't tried the lines by themselves in a viewer.  Sounds like an
>>excellent experiment and not hard to do - just put a gauge in the
>>viewer.  Better yet, since the viewers in real life had focal lengths
>>around 45 mm, to get two degrees, we need a separation of 1.6 mm.
>>


To which I replied.

>Have you tried this experiment yet, I canot say I have specifically tried
>it myself but I seem to recall that the Panum phenomena is apparent for the
>lines themselves with no slide in place and using a mounting viewer. I will
>have to check to be shure, but in anycase this would have been using the
>realist gauge or the seven perforation both of which are below the 1.6mm
>you suggest. The gauge intended for 2x2 mounting has two or three lines at
>different seperations and I think the widest is about 1.5mm .
>Unfortuneately I cut both of mine  up to make gauges to fit into my SLR,s
>for judging the infinity point distances when making hyperstereos.

I have now checked this myself and the Panum phenomena which makes one of
the pair of lines on a mounting gauge apear further away than the other in
order to set the far point, does still work for me with the gauge only.
Both with my Cassela mounting viewer and with my " Life-Like " viewer which
has had its lenses replaced by better quality ones. This I tried with both
7 and 5 perforation gauges in the case of the Cassela but just the 5
perforation with the "Life Like". Although I think the effect is more
pronounced with an actual slide present as it more obvious that the far
line corresponds aproximately to the far point of the scene even before it
adjusted to be the same.
 Both these gauges have 1.2mm difference in parallax between the two lines
but the 5 perf has 62.4mm and the 7 perf 62.1mm between the "centres" the
"Ref" line  and the first "Near" line of the line pair. I also tried the
right hand half of the 8 perf 2x2 gauge I cut up, placed on one of the
other gauges with their near lines aligned. Using the Cassela viewer I
believe I still saw the effect with the 1.5mm "far" line at perhaps 2
degrees seperation. However this gauge also has a 0.5 and 1mm far line so
perhaps it only works because they are fused first   leading up to the
1.5mm . Somewhat in the way that Julez described that after fusion at 6'
the lines could be seperated and retain fusion up to over 120' or 2 degrees
of arc.   P.J.Homer




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End of TECH-3D Digest 297
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