re: Exposure and viewer illumination

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

Dr. George A. Themelis writes

>I think that the best use of variable light intensity in viewers is mainly
>to match the ambient light.  Light intensity that looks OK at home in the
>evening will look too dark in a brightly lit environment (office, daylight,
>etc.)  Slides need plenty of bright light to look at their best.   Light
>intensity that looks OK in daylight will look too bright in a dark room.

The use as you mention above is a good one which I think is generally 
under-estimated. I agree with it and want to share a personal experience
regarding ambient light and perception of viewers. This experience wasn't
exactly 3D but I think illustrates very well the effect you describe.
It actually can also be "seen" with ones eyes being closed!

On the nighttable we have a clock radio which is directly opposite my
eyes when I sleep. We also have a night light, which of course illuminates
the room dimly. This setup poses no problems. Now what am I getting to.
Okay here is what I discovered awhile back. Once the nightlight bulb
burned out. That night I didn't replace it and guess what? The clock 
radio LED's were shining too brightly in my eyes when I was sleeping and
had to reposition it. This is the same clock radio that wasn't too bright
when the nightlight was on. The conclusion from all this is that yes
ambient light certainly does effect the brightness of stereoviews in
viewers or clockradios when sleeping!

Another similiar example are television sets and illustrates another aspect
other than the percieved brightness and is sharpness of the image. I don't
particularly see this effect myself but have read it in some periodical.
As most people know, the brightness of a television is also effected by
it's ambient light and some television sets have photocells to adjust it
accordingly. But the thing that was mentioned in the periodical was that
when viewing television in total darkness the picture would not look as
sharp as when one has a small lamp on. I remember it mentioning that it
had to be in a particular orientation for the best effect. It was explained
that what happens in total darkness (and I would imagine also 2D or 3D on
monitors) is that the iris of the eye is open wide in the dark. With a
small lamp on, the iris closes down similiar to a camera and thus the
television should look sharper. As I mentioned this is probably a subtle
point and I haven't really noticed it but that is what I remember reading.
I do remember my parents 60's B&W Sylvania television having a white neon
tube around the perimeter of the screen, which at the time thought was
for decoration. Now I wonder if they were ahead of their time and still
are, since not to many (none?) sets have this feature. Now this is making
me wonder. Maybe the background outside the stereo window inside a viewer
should be white?

>If I am not sure, I'll carry both bulbs.  That's called
>"poor man's light intensity control" ;)  Of course, there is the "even
>poorer man's control" which is based on changing the distance of the $3
>viewer from the 100W household bulb!!! ;) ;) ;) (apologies to $3 viewer
>users!)

No apologies needed. I have progressed or am progressing to a $29 viewer. 
I am working (and is rather simple) on adapting the 3Discover to be 
able to view 3D RBT mounts in it, without ruining the 3Discover or RBT
functionality. It will still be able to be used with the cassettes and
at the same time be able to display RBT mounts. The only modification to
the RBT mount required is a small 5 second grinding out of one face of
the dual plastic masks to accomodate it to the sprockets of the 3Discover. 
Also some grinding in strategic places on the 3Discover is required. As for
the light intensity this is being worked on also. Will change from
flourescent to those cute halogens 20 or 50W lamps. Of course no batteries
required, just AC. As for the changing the distance of the viewer from
the 100W household bulb, hey at least it doesn't change the color
temperature. :-)

   G a b r i e l       Ga  br  ie  l    G a b r i e l  jacob@xxxxxxxxxxxxxx
  _      you   _      _    you     _   _      you   _ 
 | \   seeing  |\   /  \seeing    / \ | \   seeing  |\
 |      _      |   /     _       /    |      _      |
 .----./ \.----.  .----./ \.----.     .----./ \.----.
 | 3D /   \ 3D |  |3D  /   \3D  |     | 3D /   \ 3D |
 '---'     '---'  '---'     '---'     '---'     '---' 


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