Video Magnifiers can be great tools and bring many hours of enjoyment to the visually impaired. They can also be frustrating for the first time user who expects a video magnifier to perform in a manner that it simply cannot and often times souring the user on the idea of using a vision aid at all. In this document, we will attempt to explain the basics of how video magnifiers work so that people new to video magnifiers can have some idea of what to expect when they purchase one. Please remember that not only is technology constantly changing but that we cannot cover all aspects of video magnifier operations and that you should check with a retailer or manufacturer for information on how a specific model works and what features it has.
Some of the common complaints people new to video magnifiers have about their capabilities are that they cannot view a whole page at the magnification that they need, that there is not enough magnification, that viewing a screen is not the same as looking at a book, the user does not like having to move the reading material or video magnifier to follow along, and that the user has trouble adapting to or learning how to operate the video magnifier. Hopefully, by the time you finish reading this article, you will understand the basic operation of a video magnifier so that you can prepare yourself or the person that will be using the video magnifier for what to expect, and you will know to ask the company that you are purchasing from if they offer free assistance with its operation.
For persons new to video magnifiers, we would like to suggest that you please read this entire document at least once. Afterwards, please feel free to re-read it if necessary or to skip between sections to make sure that you completely understand the content. If there are any questions, please fell free to contact us (Vaughn Engineering) for more assistance.
Magnification Basics
A video magnifier in its most basic form is a camera. Cameras are very similar to other magnifying devices in how they make objects appear larger. If you have ever looked through binoculars, you have noticed that the objects appear larger, but the area that you see is much smaller than what your naked eye sees at the same distance. To make objects appear larger with a camera, you can do a few things such as move that camera closer to the object, adjust or increase the lens size to zoom in, or many digital cameras can zoom in electronically. In all cases, the object gets bigger, but the picture shows less area.
Your natural eyes, in some ways, work similarly to the camera. When you are far away from something, you can see much of the area around it, but details of the object may not be as clear. If you move closer the object, it takes up more of your field of vision, it looks larger, you can see more details, but you can see less of the area around it. Take and eye chart on a wall for example. If you are standing across the room from it, you can see the chart and much of the wall that it is hanging on, but the smaller letters may be hard to read. If you move all the way up to the chart with your nose against it, the smaller letters appear larger and may be much easier to read, but you cannot see much of the wall around the chart.
How much of the reading area will you be able to see? That depends on the magnification that is needed and the size of the screen that is being used. Most new users want to see the width of a page or a newspaper column. In most cases, people that need a video magnifier need ample magnification that will not allow for that much area of the reading material to be displayed.
Let’s take, for example, a 20 inch standard screen monitor or TV. The old square type not the newer wide screens. 20 inches is the diagonal measurement of the screen not the width. We have done the math and determined that the width of the screen is 16 inches. To see an 8.5 inch wide standard sheet of paper across the width of this screen and determine the magnification that can be achieved, divide the width of the screen by the width of the paper, 16 divided by 8.5 = 1.88 times magnification. This is less magnification than you can get with a magnifying glass and is not suitable for most people investing in a video magnifier.
What if the user needs 10 times magnification? Using the same 20 inch screen as an example, to determine the width of the viewable area, divide the width of the screen by the needed magnification to determine how wide of an area can be seen with a video magnifier. Or, in our example, 16 divided by 10 = 1.6 inches. That is the width of the area that can be viewed at a time. Remember that the size of the viewable area changes with the screen size and the amount of magnification. On a portable video magnifier that has a 3 inch wide screen, at ten times magnification you can only view 3/10 of an inch at a time. So as you can see, larger screens can display larger areas at the same magnification while smaller screens display less area. On some video magnifiers that connect to a screen or monitor with a cable, the magnification can be increased by connecting it to a larger screen. In short, to view a larger area, you need a larger screen or less magnification.
Some video magnifiers have variable magnification giving the user the ability to adjust the strength of the magnification. Increasing the magnification creates larger images and less viewing area while decreasing the magnification creates smaller images and a larger viewing area. There is no way to avoid it; the size of the viewing area is directly related to the magnification needed and the size of the screen that is being used.
The amount of magnification that a video magnifier can achieve is very important to the user and is many times overlooked before a purchase is made. It is very important for the purchaser to understand the amount of magnification that the user needs before deciding on a magnifier. A magnifier with too little magnification can be useless to the user. And though it is best to have more magnification than is needed to allow for the possibility of diminishing vision, too much magnification can needlessly make the viewable area too small. We suggest that you use this handy downloadable chart to help determine and approximate magnification needed. Magnification Chart
Is there a difference?
One difference that may affect some users but not others is the type of camera used. Some video magnifiers use analog cameras, some use digital cameras, while others may use what might be considered a hybrid where a digital or electronic circuit is added to an analog camera to give it added and or enhanced features. Another difference in cameras can be whether they are color or black and white. There are Desktop, Handheld and Portable models, models that have their own screen and models that connect to the users TV, computer monitor or directly to the computer itself.
The choice of which video magnifier to purchase should be based on the magnification that is needed, the size of the screen, the users ability to operate the device (some are easier to use than others), the user's personal preferences and how they like to work, where the video magnifier will be used, what the video magnifier will be used for, the size of the area that the magnifier will be used in, and the features that the user will benefit from.
Digital Cameras
Many people have seen or used digital cameras not associated with magnifiers. Besides the popular point and shoot cameras, digital cameras can also be found in many places such as cell phones, laptops and some web cameras just to name a few. Their size, digital circuitry and software can make them very easy to use while giving them features that many analog cameras do not have.
Not all digital cameras have the same features, some have more than others and software and digital circuitry continue to evolve. Though we will not name all the features available, here are some that can be beneficial when used in a magnifier: Automatic focus, digital zoom, enhanced or high contrast black text on white background (enhances the contrast between the white background and black text to make the words and letters look sharper and clearer), reverse or negative image (reverses the color of black text and white background making the text white and the background black), enhanced or high contrast white text on black background (enhances the contrast between the black background and white text to make the words and letters look sharper and clearer), the ability to change the text and background to an assortment of colors, black and white or grayscale (produces an image similar to black and white photos or movies) and freeze frame. Digital cameras can even be in High Definition or HD (though HD cameras are overkill for video magnifiers. Because video magnifiers are usually used at close range, 3 feet or less, most cameras have ample resolution to provide a very good and clear image). It should also be known that it is not uncommon for digital cameras to need more light than an analog camera.
In can be helpful to know that there can be a couple of quirks with some digital cameras that may be a troublesome to some users while others are able to adapt to them quite easily. Whether or not these quirks are a problem for the user solely depends on the user and their ability to adapt.
If a camera has an Auto-Focus function, the closer a camera is to an object, the harder it can be for the camera to focus automatically. Some cameras handle this better than others creating less of a problem. Some cameras have a means to over ride the Auto-Focus that also allows the user to focus manually, while others require a slight momentary movement in front of the lens to make the camera attempt to re-focus.
Some digital cameras can lag slightly behind as the user is reading and scrolling. This can create a delay between when the user starts and ends the scroll and the scrolling begins and ends on the screen.
In some instances, a digital camera can momentarily fall behind in processing the image and then quickly catch up. When this occurs, the words can momentarily stop scrolling and then quickly appear to "jump" across the screen. This is similar to a computer that falls slightly behind in processing its information and momentarily slows down. Once it catches back up, it works fine and is as fast as it was before.
Analog Cameras
Analog cameras that are used in video magnifiers are not the same as cameras that use film. They are similar to the cameras that were used in older video cameras that recorded to video tape and are usually larger than digital cameras. They can be either fixed magnification or variable. Variable magnification units can be either manually controlled or electronically controlled where the push of a button activates a motor and adjust the lens or moves the camera. Focus can also be controlled manually or electronically.
Some analog cameras have additional circuitry that can give them some or all of the features of digital cameras. They often times have a wider range of magnification by having the ability to use both digital and analog magnification techniques simultaneously to achieve a higher scale of magnification.
Typically, analog cameras require less light than digital cameras and some analog cameras are low light cameras that can work in varying degrees of near darkness. Low light cameras can be beneficial for people with light sensitivity.
The auto-focus on some analog cameras can be troublesome for some users, again because of the close proximity. As with digital cameras, there is usually either means to over ride this function or a way to force the camera to re-focus.
Color or Black and White
Color cameras are very good at showing a true representation of a picture or words on a page. In fact, when magnifying, color cameras will often times show details that a person with perfect vision would not see with their bare eyes. This is not always so with black and white cameras, some times called grayscale or "mono" cameras (Mono is short for monochrome).Black and white cameras convert colors to shades of black and gray, sometimes called grayscale or monochrome. Though some low vision sufferers may actually see some objects or reading material better in black and white instead of color, black and white images can make some details indistinguishable from others in pictures and may cause problems with some printed material.
*Something to think about:
Vaughn Engineering had originally planned on manufacturing black and white video magnifiers and tested black and white cameras. During this testing of some black and white cameras that were being considered for our magnifiers, we found that in some cases certain common colors of ink on certain common colors of paper could wash out or look so faint that they could be unreadable while some other combinations made the paper appear blank.
Portable Video Magnifiers
Small battery operated video magnifiers with a small built in screen that the user can hold in their hand. Typically, because of their size, their screens are very small and there is not room for larger more powerful lenses. This usually means that portable video magnifiers will not produce as much magnification as a larger desktop or handheld video magnifier.
Many portable video magnifiers use digital cameras incorporating many functions such as variable magnification and altering the text and background colors. LED lights are a feature on some portable magnifiers making them easier to use in dim lighting.
Though portable video magnifiers can be used as the primary magnifier for home and office, their original intended use was for times when a larger magnifier that requires an electrical outlet was not practical. For example; shopping, reading menus at restaurants, or other times when magnification is needed away from a larger magnifier.
Handheld Video Magnifiers
These are smaller video magnifiers that the user holds in their hand and moves across the reading material. They are plugged in to a wall outlet for power and most connect to the user's TV in the same manner that you would connect a DVD player. Others can connect directly to computers through a USB port and software. Most are similar to a computer mouse, though they may be larger and different shapes. Most must rest directly on the reading material to focus properly (this type has lights built in) while some can be held a short distance from the reading material. Some do have their own screen and look and operate similar to a portable (these types can be much larger than most handheld units and can have larger screens than most portables).
In the beginning, most handheld video magnifiers used analog cameras and had a fixed magnification. Then digital circuitry was added to some giving the ability to manipulate the text and background colors. Now, more and more are being produced with digital cameras to provide more functionality and variable magnification.
Desktop Video Magnifiers
Desktop Video Magnifiers come in many shapes and sizes that can set on or be mounted to a desk or table. Many have their own monitors (currently some monitors are as large as 24 inches and they may be available with larger monitors in the future). Some connect to TVs in the same manner that you would connect a DVD player. Others connect to directly to computer monitors and some connect to computers through a USB port and software.
Almost all desktop models have variable magnification that is achieved either by relocating the camera, manipulating the lens, digitally or some combination of the fore mentioned. They can be very basic with just variable magnification or have a variety of functions such as automatic focus, digital zoom, enhanced or high contrast black text on white background (enhances the contrast between the white background and black text to make the words and letters look sharper and clearer), reverse or negative image (reverses the color of black text and white background making the text white and the background black), enhanced or high contrast white text on black background (enhances the contrast between the black background and white text to make the words and letters look sharper and clearer), the ability to change the text and background to an assortment of colors, black and white or grayscale (produces an image similar to black and white photos or movies), place a line across the screen for reference and freeze frame to name most of the common functions. Many desktop video magnifiers have their own light built in while others utilize the room light. Some use low light cameras that operate in very dim lighting which can be beneficial to people with light sensitivity.
Hopefully this article gives its readers a better understanding of video magnifiers, their capabilities and functions, and to realize that choosing a video magnifier is not as simple as choosing a magnifying glass. We also hope that if they are not 100% certain about a video magnifier that they will contact a manufacturer or retailer for more details.
For individuals making a first time purchase of a video magnifier for another person, we would like you to read Vision Loss and Family, an article that describes some of the problems and tensions that arise when friends and family members try to help a low vision sufferer.
Written and published by Tony Vaughn May24th 2013
