A video magnifier, or closed-circuit television (CCTV) system uses a stand-mounted or handheld video camera to project a magnified image onto a video monitor, a television (TV) screen, or a computer monitor. There is considerable versatility in types of video magnifiers available today.
Cameras with zoom lenses provide variable magnification. In most of these systems, magnification level and focus are set after choosing a comfortable and functional working distance between the camera and the material to be viewed. Some systems use an auto-focus camera. Lower cost CCTVs often use cameras that have a fixed focus and cannot vary magnification or camera-to-target distance. Most cameras also need their own light source.
- Cameras that are mounted on a fixed stand require the reading
material to be placed under the camera and moved across and down the
page. To make the process of viewing easier, a table that is movable
from the top of the page to the bottom and side to side (referred to as an
xy table) is used with most stand-mounted cameras. Stand-mounted
cameras are particularly effective for handwriting because a hand can fit
under the camera.
- In contrast to stand-mounted cameras, handheld cameras are portable systems designed for bringing the camera to the material to be viewed. They can magnify almost anything within reach, including labels on packages of food and medicine. Handheld cameras are often on rollers, which make them easier to move across a flat working surface. Some manufacturers of video magnifiers that use handheld cameras offer a writing stand as an accessory.
All video magnifiers offer the option of viewing black letters on a white background or white letters on a black background. Controls for contrast and brightness are also standard. Many video magnifiers also provide other special on-screen features and controls including underlining or overlining of text. Some systems work jointly with a computer, offering the option of sharing the computer monitor. Color video magnifiers are useful for reading materials in which color is crucial, such as maps and color photographs. A radical departure in design from conventional video magnifiers is the use of head-mounted displays (HMD). They offer portability and new ways of viewing the display. The ability to capture and save an image is also a new function that has recently become available.
Typically, video magnifiers that use a camera mounted on a fixed stand and xy table are in the $1,800 to $4,000 price range. Lower cost video magnifiers that plug into a TV are in the $400 to $1,000 price range.
Eye fatigue and other physical problems can result if the user does not have sufficient vision to read for a significant period of time without tiring. It is advisable for people considering purchasing a CCTV to have a low vision evaluation and consult with a low vision specialist who can help with determining which product is appropriate.
To view a short video about video magnifiers choose one of the following links.
Video on Video Magnifiers: Part 1
Video on Video Magnifiers: Part 2
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