Document Cameras

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DOCUMENT cameras--sometimes called visual presenters--are among the most exciting current technologies available to assist teachers in presenting formal or informal lessons. These devices can take the place of overhead projectors. They offer an array of helpful functions and features--and should be found on every teacher's desk in every classroom.

Document cameras basically place a digital camera on some kind of stand. Some have bendable goosenecks, some have mechanical arms, and some have a platform. Generally, the first two types are the most portable and the least expensive.

These "cameras" can be used with a projector, but they are generally most useful when attached to a computer and a projector or whiteboard. Document cameras can be used to display prepared papers, photographs, or a blank sheet of paper used as a blackboard replacement. Newspapers, magazines, and most books can be displayed so that all students can see the same thing at the same time. The images or objects can be magnified. Even transparences and microscope slides can be shown, usually with an adapter.

Two- or three-dimensional still or moving objects can also be displayed with a document camera. Living creatures can be displayed; objects that are too large can by shown by turning the camera head and showing a view from the side.

Most document cameras can take digital photographs that save in a variety of formats to USB flash drives, CDs, DVDs, or classroom computers. Some of the devices can make video and audio recordings as well.

This article takes a look at examples of document camera technology offered by a variety of companies. Keep in mind that this information is not intended to provide a detailed review of these devices. There are certainly many more models and companies producing document cameras than those mentioned here.

THE FEATURES

Document cameras haven't been around all that long, and they have changed a lot since they were first introduced. Today's cameras offer a variety of features that should be carefully considered--image quality, zoom, image capture, autofocus/autoexposure, pass-through mode, fixed arm or gooseneck, and more.

Image quality is a function of resolution and other factors. Resolution, of course, refers to the number of pixels displayed. The more pixels, the higher the picture resolution and detail. XGA resolution is 1024x768, SXGA resolution is 1280x1024, and UXGA resolution is1600x1200. Usually, the more expensive the document camera, the better the image quality. Higher image quality is great for capturing still images to use with a computer--but this won't be of much use if the attached projector has a lower resolution.

The zoom feature on today's document cameras is wonderful. Optical zoom is better than digital zoom. Some document cameras have actual zoom lenses, but some "zoom" by moving the lens closer to the object on display. Something as small as a dime can be enlarged, with its tiniest features projected and visible to an audience. Some cameras can zoom in on text as small as 8-point in size. Before buying a document camera, it is important to be sure the device can clearly display at least 12-point text.

All document cameras can capture images for real-time display; most of these devices can also capture images and save them as JPEG files to be retrieved later. The way the images are moved to a computer or a whiteboard can vary from one camera to the next. Some document cameras are hooked to a computer through a USB cable and use special software to transfer images. Some have a slot for the same kinds of memory cards used by digital cameras; some can use memory sticks. Document cameras that use memory cards or memory sticks do not require special software or a computer connection.

The autofocus/autoexposure functions included with many newer document cameras are really useful. …