You Need To Know
About Document Cameras
Remember the days when high-tech presentations were limited to overhead projectors and transparency sheets? Today, technology has given birth to a wide variety of options such as document cameras. Also known as visual presenters or Elmos (though Elmo is a specific brand name), document cameras allow educators, court room attorneys, or anyone who wants to give an effective presentation the right tool to do so. Read below for more information on how to choose the perfect document camera option for you.
- Data Projector (the most common display method)
- Large enough for number of people to view it comfortably
- Computer Monitor
- Good for small meeting rooms or If there is no access to data projector
- Use images with software such as PowerPoint
- Switch from computer images to document cameras with a touch of a button
- Television Screens
- Good for small meeting rooms
- or if no access to data projector
- Fixed Installations
- Great for using on a stage or in a library
- Generally full-featured
- Variety of options
- Portable Document Cameras
- Greater Mobility
- Basic to fully-featured models
The resolution of the document camera you choose will determine the quality of the image that is portrayed.
- number of lines
- number of pixels (most common)
Document cameras are categorized by their resolution in the same manner as data projectors.
It is important to match your document camera resolution, or input resolution, with your output resolution, whether it is a data projector or a computer monitor.
While not directly related to resolution, frame rate has a great impact on the overall appearance of the image.
- Frame rate is the number of times the image refreshes per second and is often referred to as fps (frames per second).
For example, a presenter that refreshes 30 frames per second will have much smoother movement than one that refreshes 15 frames per second.
There are three ways to make objects appear larger when using a document camera.
- Bend the gooseneck so that the head is physically closer to the object
- No extra cost
- Optical zoom involves a physical movement
- no degradation in quality of image
- may be more expensize
- Digital zoom resamples the image to make it appear larger
- Slight degradation of quality
- less expensive than optical zoom
Many document cameras are equipped with lights that allow you to brighten the subject and dispel shadows. The type of lighting you need will depend on the room in which you plan on doing your presentation. In a bright, well-lit room, lighting may not be needed; however, in a dark room or room with uneven lighting sidelights can be used. A special type of light is a backlight, which allows you to use transparencies, X-rays or slides.
A growing number of document cameras / visual presenters allow you to actually capture and store images for later use. Some more elaborate presenters use memory cards for storage but most utilize internal memory that can later be downloaded into a computer.