If you haven’t been to a classroom or lecture hall recently, then you are in for an audiovisual treat. The overhead projector has evolved into a cool, quiet, modern product called a digital visual presenter.
The overhead projector first was followed by a gizmo called a document camera. It could take a still image or a video of a sheet of paper or an object and feed that to an LCD projector, such as is commonly used for PowerPoint presentations or video. The document camera had a cold light source or sources for illuminating the subject matter. It also had both autofocus and zoom so the instructor could highlight a detail. This is a much better than an overhead projector. There is no more glare, hot air, blower noise, marker ink on hands, or transparencies to clean. You can see a two minute YouTube video on a digital document camera here.
Then the document camera was in turn followed by an even fancier gizmo with memory and input switching. The latest generation is variously called a digital visual (or video) presenter, a digital presenter, visual presenter, or a visualizer. A speaker now can easily switch between live video or still images, stored images, and a PowerPoint presentation. Click here for a two minute TeacherTube video of a visual presenter.
Some visual presenters fold for portability, as seen in this brief Youtube video of a Samsung model. There is a bewildering variety of designs. For example, ELMO makes units ranging from a four pound portable for accompanying a notebook computer to a unit for permanent mounting on a ceiling.