Re: [photo-3d] BULBS II

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

To answer the second part of Sy's question ("which viewers
can take a halogen bulb?") the answer is that if you modify 
the halogen bulb by shortening the top then it will fit in 
ALL the viewers.  The View-Master viewers are among the
toughest with the least amount of space.  For these viewers
you can file out the soft contact. Then the halogen bulb
will fit.

This page:

http://home.att.net/~drt-3d/catalog/bulbs/HalogenTips.htm

Gives tips for using the halogen bulbs.  It shows the bulb
modified at the top and bottom. Also discusses the power
requirements for these bulbs and also mentions the
distracting shadows/hot spots which might be noticeable
with some viewers.

Because of the thick glass envelope, the halogen bulb
can be "frosted" (i.e. etch/roughen the glass via mechanical
or chemical action) to give more uniform illumination.  To
quote from this page: "When this is done, the light is not 
emitted from the very small filament but from the considerably 
larger glass envelope.  The result is uniform illumination at 
the slight expense of light intensity.  Bulb-induced shadows 
disappear and viewer-induced shadows are softened, just like 
they are in real life when the sun is blocked by a cloud."

The same page also gives a diagram showing viewer illumination 
as a function of voltage for 4 different light bulbs: No. 14, 
No. 245, 0.5A halogen and 0.8A halogen.

VERY IMPORTANT:

Using the right bulb is only one part for achieving good
illumination (= white, bright light of even intensity) 
in a viewer.  The following page:

http://home.att.net/~drt-3d/catalog/bulbs/IlluminationTips.htm

Gives tips for improved viewer illumination.  The summary is 
as follows:

1. Use a new/bright reflector
2. Increase secondary reflections
3. Use a bright light bulb
4. Use adequate power source 
5. Clean electrical contacts 

George Themelis

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Was the salesman clueless? Productopia has the answers.
http://click.egroups.com/1/4633/8/_/160438/_/959552251/
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