Re: 116 vs 716

[P3D KENNETH LUKER <KLUKER@xxxxxxxxxxxxxxxxxxxxxxx>]

This is bringing up a previous topic, but it may be of some interest 
to see a more complete test of the comparison of TDC 116 and 716 
projectors.  I set up the two projectors again just before Christmas 
and compared the illumination at the screen under more closely 
controlled conditions that my previous test.  The findings are as 
follows:

First, I put the projectors at about twenty feet from the screen and 
loaded the same slide into each projector sequentially, then measured 
the exposure value of the brightest area of the image (a bright 
window, almost clear on the transparency), with each lamp singly and 
with both lamps.  Then I moved the 716 closer to the screen until the 
image size was exactly the same as the image of the 116.  As in my 
previous test, the 116 had 5-inch lenses and 500 watt bulbs, and the 
716 had 4-inch lenses and 750 watt bulbs.

Bulb            116            716 same dist       716 same image size
left only       5.1             4.4                 4.8
Right only      5.2             4.5                 5.05
Both            5.8             5.1                 5.65

I then repeated the experiment with no slide in the carrier:

Bulb            116           716 same distance  716 same image size  
Left only       5.5             4.75                5.25
Right only      5.5             4.9                 5.5
Both            6.3             5.55                6.2

The apparent accuracy of my readings is misleading.  I used a digital 
light meter that displayed the nearest 1/10 ev, so when my trials 
resulted in readings split half the time between two adjacent values, 
I split the difference in the table.  If the readings were almost 
always one value, I used that value.

I'm aware that these values are a measure of the combination of 
projector, lamp brightness, lamp age, lens length, polarizer 
transmission, etc., but they represent real systems as they were 
available to me.  

Because by every measure the TDC 116 and its lamps and lenses gave me 
a brighter image, I'm keeping mine!  Next time I have the 4-inch 
lenses available, I should try switching lenses in the 116 and 
running another test.
Ken Luker




_______________________________________________________________

Kenneth Luker, Assistant Director
Systems and Technical Services
Marriott Library
University of Utah
Salt Lake City, Utah
KLUKER@xxxxxxxxxxxxxxxxxxxxxxx


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

End of PHOTO-3D Digest 1776
***************************
***************************
 Trouble? Send e-mail to 
 wier@xxxxxxxxxxxxxxx 
 To unsubscribe select one of the following,
 place it in the BODY of a message and send it to:
 listserv@xxxxxxxxxxxxxxx 
   unsubscribe photo-3d
   unsubscribe mc68hc11
   unsubscribe overland-trails
   unsubscribe icom
 ***************************