P3D Re: Projection Technique

[Dan Wenz <djwenz@xxxxxxxxx>]

On Tue, 7 Jul 1998, Dr. George A. Themelis wrote:

> Here is one way to check it:  Rotate your polarizing glasses.
> Is it getting worse?  Then it is ghosting.  When you project such
> small images it is possible that ghosting is becomes more noticeable
> because of of the brightness of these images.  -- George Themelis
> 
> >> What you describe sounds like classic projection ghosting. 
> 
The "secondary" images I see are actual (dim) duplicate images of the
slide in the projector - around a foot and a half away from the primary
image. If I just turn the right lamp on, for instance, I will see the dim
image about 1 1/2 feet to the left of the primary image. It comes from the
LEFT lens, and visa versa when the left lamp is turned on with the right
side off :-)  The projector has a 5" lens set, and is around 3 1/2 feet
from the screen. The dim image has the same polarization orientation as
the main image - rotating the glass to dim the main image has the same
effect on the second image.


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