MC Squared Systems Design Group


Overhead projectors are still the most common A/V aid in training environments. They need to be located within arms length of the lecturer so they can write on the light table. This usually puts the projector very close to the front wall in a training room, and there's often a need to have the blackboard available as well. The default projection surface is usually above the blackboard, which results in drastic image distortion known as "keystoning". When this is combined with a short depth of field on the projector lens, part of the image will also be out of focus. This is not a critical problem when the material is large hand-writing on acetate, but when used with an LCD panel and computer graphic presentations, this image distortion reduces the likelihood that students will be able to read smaller print. Keystoning can also be a problem when slide or video projectors are located too far above or below the screen centreline.

Careful analysis and design of projection lines and projector and screen locations prevents keystoning from being a significant problem.

badly keystoned image

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MC Squared System Design Group, Inc.

323 - 901 West 3rd Street, North Vancouver, BC V7P 3P9
Phone 604 - 986 - 8181   FAX (604) - 988 - 9751