January 2004 Issue  Volume 5  Number 1

Product Evaluation

Quite a Display: A Review of Two Video Magnifiers

This article reviews two video magnifiers: the Merlin by Enhanced Vision Systems and the Prisma by Ash Technologies. These two were chosen because of the unique offerings they each bring to the field of low vision. The Merlin and the Prisma have made waves because of their comparatively low cost for color units.

What follows is a review of these two units, along with the advantages and disadvantages of each model. A "bottom line" evaluation and summation is then presented for each machine. A direct comparison of the models is not possible, since each unit has unique characteristics and features.


The Merlin is an "in-line" closed-circuit television (CCTV)--one that includes both the camera and monitor. Although in-line units generally have the monitor aligned on top of the camera unit (in line), the Merlin has the capability of positioning the monitor to the side of the camera unit. It caused quite a stir in the field by becoming the first autofocus color unit that costs less than $2,000. The degree of zoom magnification can be changed either with a large dial (positioned in the center of the controls) for continuous adjustment or with preset locks, allowing you to set and select two main preferred specified sizes of magnification, depending on the print size you are reading.

Figure 1: Photo of a man looking at a picture of a baseball player with a Merlin CCTV.

Caption: The Merlin CCTV.


In addition to its lower cost for a color in-line unit and a three-year warranty, with an optional lifetime warranty on the camera for an additional $100, the Merlin's monitor comes in two sizes: 14 inches or 20 inches. Furthermore, the large, ergonomic, and easy-to-control buttons are all front mounted, and the push buttons are concave and large. In contrast, many other comparable units have controls on the side or in more difficult locations for the user. The Merlin has the largest working space of any X-Y table for reading and other tasks. Also, the monitor is not permanently mounted on the camera table, so you can place the monitor at the desired position and height, which may allow for enhanced posture and ergonomics while viewing the monitor. The optional voice recognition for magnification controls may be helpful for persons with physical impairments, such as arthritis, or for older persons who have difficulty with controls. A preset magnification-level button helps you go immediately to either of two desired magnification levels that you select and set. Other advantages include an autofocus camera and an optional "Color Select" feature to select various color combinations when reading.


Despite its advantages, the Merlin has a number of disadvantages, including a relatively poor contrast of the control buttons against its background color plate, decreased resolution in the highest magnification levels when used in the color mode, and some reported problems with the locking and quick-release mechanism on the X-Y table. In addition, the current models have a steel webbed-based frame, compared to the plastic X-Y table, which was lighter in weight, in the original model.

The Bottom Line

The Merlin is a reliable, easy-to-use CCTV with a great warranty, for an affordable price.


The Prisma is a fold-up, portable color CCTV that is lightweight (weighing less than 3 pounds) and can be transported in a lightweight carrying case to desired operating locations and connected to a conventional TV monitor of any size. Unlike handheld CCTVs, the camera does not need to be moved by hand, which requires considerable tracking skills. Instead, the camera remains stationary, and text or objects are moved underneath the adjustable camera. The arm housing the camera can be raised or lowered, which adjusts the amount of magnification. The lens is manually focused.

Figure 1: Photo of the Prisma focused on a magazine with the text appearing white on black on a television monitor.

Caption: The Prisma.


In addition to its relatively low cost for a stationary CCTV and its portability, the Prisma has minimal controls, is easy to operate, has fairly good color for an inexpensive unit, and can be used with any size monitor.


The disadvantages of the Prisma are its reduced resolution and image quality, compared to most more expensive in-line units; its manual focus; and the fact that the arm that holds the camera is less sturdy and hence may loosen over time as the camera is moved and the height of the arm is altered (to adjust the level of magnification). In addition, the X-Y table is not movable; you must physically move text or materials under the camera.

The Bottom Line

The Prisma is a portable, inexpensive color CCTV that does not require you to hold and move the camera. However, it generally requires you to move the materials under the camera and has a somewhat diminished resolution and image quality than do standard in-line units.


Both of these CCTVs provide unique offerings to the field of low vision. Each holds a promise for the future: the Merlin because of its breakthrough in lowering the cost of color CCTVs and the Prisma because of its portability of a non-handheld color CCTV at an affordable price. Neither is without some need for improvement, yet each provides some solutions for the present and a hope of even better things to come.

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Product Information

Product: Merlin

Manufacturer: Enhanced Vision Systems; 17911 Sampson Lane, Huntington Beach, CA 92647; phone: 714-374-1829 or 800-440-9476; e-mail: <info@enhancedvision.com>; web site: <www.enhancedvision.com>. Price: Black and white, with 14-inch monitor: $1,795; color, with 14-inch monitor: $1,995; color, with 20-inch monitor: $2,145.

Product: Prisma

Manufacturer: Ash Technologies, Freedom Vision; 615 Tami Way, Mountain View, CA 94041; phone: 800-961-1334; e-mail: <info@freedomvision.net>; web site: <www.freedomvision.net>. Price: $995.

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How Closed-Circuit Television Users Develop Computer Vision Syndrome by Alec F. Peck and Mark Uslan
Portable Video Magnifiers in Museums by Mark Uslan and Ike Presley

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