3M
Multimedia Projector MP8610
Theory and Diagrams
3M 1999
4-6
4-7.
Keystone Correction
A correct projection image on the MP8610 should be
square and in focus. A projection image that is wider at
the top and has a softened focus has keystoning.
Keystoning is visible on the MP8610 when the
projection to screen angle is greater than sixteen degrees.
As the front of the projector is raised the projection
angle increases. At sixteen degrees the projection image
is still square and in focus, at nineteen degrees
keystoning can be seen.
The MP8610 is keystone corrected at a ratio of 3.9 to 1
to provide a square focused image as shown. Restated,
for every 3.9 feet of projection distance the image is
raised 1 foot. This feature allows for 80% of the
projection image to appear above the lens center with
only 20% appearing below.