There is a vast array of choices available in optical and video camera magnifiers. The first step in choosing a magnifier is to define your goals and requirements. What tasks do you want to perform that you are having trouble with? Where will you be using the magnifier?
Every device has advantages and disadvantages. An auto mechanic might need a magnifier mounted on prescription eyeglasses so he has both hands free to work. A student who needs to capture images from the front of the classroom might choose a camera-like telescopic device attached to a portable video camera magnifier. While you might choose high-powered glasses for sewing you would not choose them for chopping vegetables.
A small, handheld magnifier, which greatly enlarges a few words or sentences on a page, might be good for reading labels and recipes but inadequate to help you sustain the concentration needed for to read a novel, which requires an expanded field of view and the ability to scan ahead in order to see and process information quickly.
How much magnification?
Bigger is not alway s better. The 6x magnifier is not always a better choice than a 3x. The higher the power, the smaller the area you see.
- A lower power magnifier will have a larger diameter or field of view but but will create a smaller image.
- A higher power magnifier will have a smaller field of view but the image will be larger.
As a general rule, in order maintain the largest area of view, chooset a magnifier with the least power you can get away with.
Magnifiers come in different strength.
Low power magnifiers
The lower the power the larger the diameter can be. For arts and crafts and viewing pictures a round magnifier may be preferred; for reading and writing a rectangular one can save some weight.
Medium power magnifiers
As the power increases, the depth of field decreases and the need for accurate focusing increases. This is where stand magnifiers have an advantage, especially for those with a tremor, with arthritis or with other problems that prevent them from holding and moving a magnifier for a prolonged period of time.
High power magnifiers
As the power increases, the field of view decreases. A stand is usually required. Most must be held close to the eye where the field of view is largest.
Some hand and many stand magnifiers are available with built-in light sources. There are several trade-offs to consider.
- Magnifiers with built-in illumination are heavier than their counterparts that rely on external illumination.
- While the most portable, battery powered light sources are heavier and batteries run out. A transformer can provide lasting power, but requires the proximity of an outlet. 120V sources are only practical for the larger magnifiers on a movable arm.
- Halogen bulbs drain batteries fastest and are best used with a transformer. LCD bulbs are now available and provide a high light level.
Keep in mind that the benefits of optical devices such as magnifiers can be enhanced by combining them with non-optical strategies such as increased and strategically placed lighting, glare control and contrast emphasis.
For most tasks improved illumination can compensate for a lack of contrast, so it is important to pay attention to creating a good reading environment and not rely entirely on the magnification.
While you can purchase low vision devices on your own, a low vision specialist can help you identify the devices best suited to your needs and teach you the most effective ways to use the devices for your specific requirements.
A magnifier that might help someone with peripheral vision loss, for example, might not help someone with central vision loss. Selecting a magnification range for a magnifier is the result of vision tests such as visual acuity, an evaluation of your functional vision, and trying out the many devices that mght fit your needs.
As well, if you are using multiple devices, a specialist can help you select the most effective combination of magnifiers, lighting and other devices.
|Pros||Frees the hands; wide field of view ; greater reading speed for continuous text; binocular vision, up to 10D; cosmetically acceptable|
|Cons||Close reading distance uncomfortable for some and may obstruct illumination; not convenient for spot reading (labels, price tags); may be too close for writing.|
Hand-held magnifiers, illuminated and non-illuminated, are ideal for short-duration near-vision tasks such as reading a prescription bottle or a menu. Magnifiers with chains or cords can be worn around the neck.
|Pros||Lightweight, longer, more customary reading distance; inexpensive; wide range of magnifications; socially acceptable; handy for spot reading (price tags, a recipe while cooking).|
|Cons||Only one hand free; difficult to focus if your hand is not steady; the stronger the magnification, the less you can read at a time.|
Magnifiers mounted on stands are more comfortable for reading and writing and other near-focus tasks than a hand-held device, as well as freeing up both your hands for activities such as sewing, crafts or doing household repairs.
|Pros||More stability – maintains focal distance; wide range of magnifications; you can write underneath; automatic focus.|
|Cons||Can be difficult to get sufficient light between the lens and the object you’re viewing; must move as you read anything large; not good for writing; narrow field of view.|
Magnifiers mounted on a movable arm with built-in illumination.
|Pros||Avoids reflections on the surface of the lens; especially useful for hands free operation as for arts and crafts.|
|Cons||Reading requires movements of the head or of the book to span a wider page..|
This mode of illumination is an advantage since it avoids reflections on the surface of the lens. This type of magnifier is especially useful for hands free operation as for arts and crafts; reading will require movements of the head or of the book to span a wider page.
Illuminated stand magnifiers have a built in (AC or battery) light source.
|Pros||Even light source, wide range of magnifications, you can write underneath|
|Cons||Often difficult to write under, larger than models without lighting|
Handheld telescopes (monoculars) are used for viewing things at a distance such as TV, sporting events and theater.
|Pros||Small, portable and inexpensive; easier focusing than stand-mounted.|
|Cons||With a very narrow field of view they are suited best for spot viewing, such as reading street signs; require a steady hand to keep the image in focus and clearly focused,|
Spectacle-mounted telescopes, attached to an eyeglass frame used with one or both eyes, are used for viewing things at a distance and are used for activities such as watching TV, attending a sporting event or theater. In some states you are allowed to use a bioptic telescope mounted on the top of eyeglasses for driving and reading road signs. Spectacle-mounted microscopes are similar devices for close-up viewing.
|Pros||You can switch between the telescope lens and the normal eyeglass lens; new systems are smaller and more cosmetic than earlier versions; are more stable than hand-held telescopes.|
|Cons|| Difficult to move about while looking through due to distorted depth perception; decrease the light,, which can be problematic for someone with poor contrast sensitivity; require considerable concentration and quick reaction times for driving.
High Plus eyeglasses are not separate devices but rather special lenses mounted on eyeglass to provide higher power magnification to bring an object closer.
|Pros||Lightweight, less obtrusive alternative to spectacle-mounted microscopes.|
Video magnifiers, combining a mounted camera and viewing screen, electronically magnify and display what you want to magnify. Good for reading, writing, looking at photographs and catalogs, or doing crafts. They come in a variety of sizes. Some can be connected to your personal computer. Video camera magnifiers can include autofocus, glare and contrast control, and a choice of screen size.
|Pros||A more comfortable reading posture as you don’t need to maintain a constant distance; allows writing at high levels of magnification; greater magnification across a larger field of view than an optical magnifiers; adjustable magnification for different tasks; auto focus; some models offer image processing for enhanced color and contrast; some models save “snapshots” of previously-seen images.|
|Cons||Power requirements; cost.|
Handheld video magnifiers, or portable video magnifiers, generally have to stand on or rest against the reading material in order to work. Handheld video magnifiers generally have a small integrated display, and some can send their signal to a computer or television. Like handheld magnifiers they are useful for reading bills and receipts, timetables, ATM displays, menus, price tags, etc., working on hobbies, reading maps and directions, and the like.
|Pros||Greater magnification across a larger field of view than an optical handheld magnifier; auto focus; some models offer image processing for enhanced color and contrast; some models save “snapshots” of previously-seen images.|
|Cons||Power requirements: access to outlet or need to recharge battery; cost.|
Smartphone /tablet apps now turn your smartphone into a portable video magnifiers.
|Pros||Far less expensive than a dedicated magnifier; does not require carrying another device; has all functions found in portable and desktop video magnifiers such as color schemes and “freeze” frame.|
|Cons||5X magnification less than dedicated magnifier; your smartphone’s screen resolution may not be as high as that of a dedicated magnifier.|