Overhead projectors are devices used to project images onto a screen. The size of the display is dependent on angle of projection and the distance between projector and screen. Overhead projectors are typically used in classrooms and conference rooms.
In order for a large classroom to see items clearly, the overhead projector needs to be at the perfect distance and angle. Panoramic views are very difficult to achieve and the inability to read slides can be distracting to observers.
Overhead projector bulbs are expensive to replace. Average cost for a projector bulb at OfficeDepot.com is $300. To purchase from ProjectorZone.com, bulbs ranged from $150 to $400.
Overhead projectors are large and bulky and usually require a cart to transport from venue to venue.
Using an overhead projector, slides require constant writing and erasing, and book pages can be difficult to discern.
Overhead projectors are an outdated technology; it is much easier to create PowerPoint presentations and display them on a computer in full color using a regular projector.