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Re: [photo-3d] projector brightness


  • From: "John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>
  • Subject: Re: [photo-3d] projector brightness
  • Date: Sun, 15 Apr 2001 10:04:08 -0700


----- Original Message -----
From: "georges belieres" <georges.belieres@xxxxxxxxxx>
To: "groupe 3d anglais" <photo-3d@xxxxxxxxxxxxxxx>
Sent: Sunday, April 15, 2001 8:25 AM
Subject: [photo-3d] projector brightness



2. I think the process of adjustment of the lamp by respect to the spherical
mirror, given by J.R.is hazardous, because superimposing the 2 images of the
filament risks to create overheating to it.
 I want to mention the articles written in ' 89 by Stan Speel and Colin Clay
(Stereoscopic Sty) in which you can find full details about :adjusting
projection lamps, cooling, screen brightness and so on . They recommand to
adjust the position of the lamp in such a way that the primary image of the
filament and the reflected image take place one above the other, with egal
dimensions.These two images "fill" or "light" a larger surface on the pupil
of the lens, and consequently, provide a better optical efficiency of the
light beam.

Another good reason for opting for lamps that have their own reflectors
built in.  The reflector position has to be configured such that not only is
the filament image not redirected back to the filament, but also that the
shape (aspect ratio) of the resulting primary-plus-reflected source is
similar to that of the projection aperture (usually the shape of the slide
mask itself).  If it is not, the extra area is wasted.

Some filaments are tight wound (little or no space between strands as viewed
from the front).  These require the complete displacement, either vertically
or horizontally (depending upon the aspect ratio and orientation of the
filament in the lamp) as mentioned above.

Others are open wound, with a space between each strand approximately equal
to the size of each strand.  These are specifically designed for the purpose
of allowing the reflector to "re-image" the filament strand "images" in
between the actual filament strands.  Check which type your bulbs have
before adjusting the final position of the sockets and reflectors.   This
information is usually available from the OEM (original equipment
manufacturer) of the bulbs.

Osram, G.E., Sylvania, Phillips, and other OEMs usually have data sheets
(check out their web sites) on the lamps they manufacture, as well,
sometimes, as to recommended sockets for them.  At least, they have
"contact" pages with phone numbers, etc., where you can inquire about
recommended socket sources.

JR


 

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