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. Being able to capture and save an image is also a new function that has recently become available.
Typically, video magnifiers very in price depending on the size of the monitor and the features included with the unit. Video magnifiers that plug into a TV are generally in a lower price range.