[photo-3d] Re: Projector Brightness

[<donaldparks@xxxxxxxxxx>]

George Themelis wrote:

Steve Spicer has replaced the older bulbs with
modern
24V/250W halogen bulbs (these are the same bulbs
used
in the RBT projector).  Even though these bulbs
have
HALF the wattage rating of the older 500W bulbs,
they
produce a brighter image!  Steve reported that the

brightness of his TDC projector is the same as the

brightness of the RBT projector!  (In my
measurements
at home, the RBT projector is brighter than the
TDC.
I will measure and quantify the difference.)

Why are these bulbs better?  Because they have
smaller
filaments and all the light goes through the
optical
system of the projector (this is not the case with

the old bulbs).

   What are these bulbs shaped like?  Are they
like the bulbs used for Ektagraphic projectors
with the molded reflector that surrounds the
filament?  I think one reason reflector bulbs are
more efficient is that the reflector comes closer
to surrounding the filament.  Light emits in all
directions from the hot filament.  On the older
bulbs a large percentage of this light escapes
from the sides and is not captured by the
projector optics.

     I'll be interested in hearing how bright your
new RBT is compared to your older TDC.  I was
really surprised that my Realist model 81 was a
lot brighter than the TDC using exactly the same
bulbs.  I'm going to check the polarizers on the
Realist to see if they've faded or something.

Don Parks


 

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