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Narrator: Video magnifiers allow individuals with low vision to place text, graphics, or even objects under a video camera...and then have the selected image enlarged and displayed on an electronic viewing screen such as a computer monitor or standard television.
There are five basic types of video magnifiers: desktop models, flex-arm camera models, head-mounted display models, hand-held camera to TV models, and a variety of portable and pocket models. In this segment we'll look at the desktop model and the flex-arm camera model.
The desktop video magnifying unit shown here has a standard computer monitor sitting atop a one piece structure that houses a video camera, system controls and the proper illumination for functioning as a camera stand. The video camera and appropriate lighting focus downward towards a 14 x 16 inch moveable platform where the objects, in this case a magazine, can be viewed.
With reading material and the appropriate page positioned under the camera, the user watches the monitor and moves the platform on which the reading material sits, rather than the magazine itself, when reading across and panning downward. Think here of the movement as that of x and y on a horizontal graph axis. Large and easily distinguishable controls allow for: automatic or manual focus, image sizing, brightness contrast control, and color adjustment. Image color and background can also be reversed based on personal preference and ease of viewing.
Users first learning to operate a desktop model often have problems manipulating the viewing table. They find it difficult to keep lines of text straight as they read. As they move the table from right to left, the line of text may move up or down. This movement can lead to a feeling of motion sickness and nausea and to counter this problem, better quality models have a control on the viewing table referred to as the friction brake. Adjusting the friction brake allows users to move the table left and right without accidentally moving it up and down at the same time. In most cases, this adjustment will eliminate the problem of motion sickness.
Another problem encountered by some users is locating the beginning and end of lines, particularly when reading text in multiple columns. As users read across a line, they may inadvertently move into the next column and, suddenly, the line they're reading doesn't seem to make sense. In adjusting the table to locate the beginning of the next line, they may then move it too far and go back to the preceding column of text. This extra movement at the beginning and end of lines of text slows down the reader and reduces their reading efficiency.
Better quality video magnifiers provide a feature on the viewing table to solve this problem, which is called a margin stop. With this feature, users can loosen the margin stops and place them all the way to the outer edges of the table. They then move the table to a position where the beginning of a column is displayed on the left edge of the monitor and adjust the left margin stop until it stops at the desired position. Next, they move the table to a position where the end of the column is displayed on the right edge of the monitor and adjust the right margin stop until it comes to rest in the desired position. The reader can now begin reading and the table will stop at the end of the column. They can then move quickly back to the beginning of the line without having to visually locate it. Proper use of the friction brake and the margin stops can greatly increase a user's reading efficiency.
This unit and ones like it can magnify an image from 3 to 60 times on a 20 inch monitor and facilitate reading everything from books and newspapers to prescription bottles. Pairing the video magnifier with a computer monitor generally means a lack of portability so these units generally are used at a fixed location in homes or an office. They are priced in the range of $2,000 to $3,500 with the monitor included.
In a similar fashion but a different configuration, flex-arm video magnifiers take the video camera out of the camera stand and mount it onto a moveable arm above the material to be viewed. The controls for this flex-arm unit are mounted on the flex-arm with the camera. Most all of the features of the desktop model previously discussed can be found on flex-arm video magnifiers. Those include zooming in and out on an image, automatic or manual focus, brightness, contrast and color control, and the ability to reverse the color of image and background. The feature that differentiates flex-arm video magnifiers from the desk top models we have just seen is their ability to view and display objects at a distance. With a few quick and simple sets that include moving the flexible arm, repositioning the camera and swinging the close up lens out of the way a flex-arm video magnifier can view and focus on other objects beyond those on its camera stand platform such as writing on a chalkboard, a sign on a wall, or slides in a presentation. Here a printed sign's image 10 feet away is clearly displayed.
After viewing distance information, users can quickly readjust the camera to examine materials on the viewing table. Pricing for flex-arm video magnifiers is comparable to the desk top units...putting them in the $2,000 to $3,000 range without monitor.
Please view Part 2 of Video Magnifiers for information on the other types of video magnifiers.