Frequently Asked Questions
What is the best type of Magnifier for a Computer Screen?A number of companies sell Magnifiers that can be used in conjunction with a Computer. These Magnifiers typically use fresnel lenses and they mount from the front of a Computer Screen. Carson does not sell or market Magnifiers that mount to Computer Screens. These Magnifiers are not very effective, and Carson does not recommend them since the disadvantages far outweigh any advantages. The pros and cons of using Computer Screen Magnifiers are listed below.
Computer Screens come in a variety of shapes and sizes. It is difficult to come up with one size Magnifier that will fit every Computer Screen.
Most Computer Screen Magnifiers magnify just 0.5x. The buyer should be very skeptical of any manufacturer's claim that their Computer Screen Magnifier magnifies more than this. The magnification of a Computer Screen Magnifier is constrained by the optical principals relative to its use. Any company claiming that their Computer Screen Magnifier is more powerful, is likely exaggerating the truth.
Computer Screen Magnifiers are typically made using fresnel lenses. Computer Screens by nature are large, and a fresnel Magnifier lens can be made in a large sheet format. Frensel Magnifier lenses by design do not produce clear and crisp images. Hence using such a magnifying device for an extended period of time might strain the users eyes.
It is possible to purchase an inexpensive computer mouse that can magnify a portion of your Computer Screen.
You can adjust the settings on your web browser to be able to surf the internet and view pages with larger fonts.
Some keyboards are equipped with zoom functions that allow you to quickly zoom in and out of most documents.
How does Carson measure Magnification?Magnification, also referred to as magnifying power, depends on the focal length of the lenses used in an optical device. At Carson Optical, we calculate the magnification based on measurements of the actual product, not the theoretical properties of the lenses. We use optical measurement equipment, such as a lensometer or lens clock, to measure the power of a lens. This provides the user with much more accurate results of magnification, compared to other methods which are based upon the lens mold or intended design that might not correspond to the real life product.
Our advertised magnifying power (MP) is based upon the standard industry equation for the maximum magnifying power corresponding to ideal viewing conditions, and depends on the diopters of a lens or lens system. The diopters of a lens is equivalent to the inverse of the focal length in meters.
MP = D/4 + 1
The diopter value (D) used for this calculation are based on empirical measurements from actual samples of the individual lens or lens system, using a lensometer and/or lens meter with a confirmed zero and calibrated to at least two points using known reference standards. The testing is repeated over a sufficiently large sample set to calculate the average actual magnification. The results are converted to magnifying power and rounded to the nearest half power. For example, magnifying powers between 2.25-2.74x are rounded to 2.5x and 2.75-3.24x are founded to 3.0x.
What are the advantages of Acrylic Magnifying lenses?Acrylic Magnifiers are extremely lightweight and durable. They are shatterproof and difficult to break. Acrylic material also makes it possible to have a smaller, more powerful Magnifier inset in the larger lens. More than 90 percent of Carson's Magnifiers are made using Acrylic lenses.
What is a Fresnel Magnifier?A Fresnel Magnifier (pronounced "fre-nel") is a flat Magnifier that is produced by stamping a series of annular optical grooves on to a flat sheet of acrylic or PVC. Fresnel Magnifiers use far less material than a typical double-convex Magnifier Lens, so they are typically very light and thin. The "flat" profile of a Fresnel Lens makes them ideal for a purse or a wallet. Another added benefit of a Fresnel Magnifier is the size of the actual lens. There are very few size constraints in producing Fresnel Magnifiers than with other lens configurations. Hence, Fresnel Magnifiers can be made in page-size or larger. One disadvantage of Fresnel Magnifiers is the "sharpness" of the image. Fresnel Magnifiers generally cannot produce as sharp an image as a double-convex Magnifier lens. To see all of Carson's Fresnel Magnifiers, visit the Sheet & Bar Magnifier pages.
What is a Linen Tester?A Linen Tester, often referred to as a "thread counter" is most commonly know for its association with the garment trade. Historically, Linen Testers were used to count the number of threads within a fixed area of fabric. Linen Testers have a measuring scale on their base, and they typically fold flat for storage. Today, Linen Testers are used in the printing industry to see how inks lay on a printed surface. Linen Testers are sold in varying magnifications or optical configurations. Carson branded Linen Testers can be found on the Folding and PopUp Magnifiers section of this website.
Is a Magnifier with the highest power the best for me?Not necessarily. The higher the Magnification the shorter the focal distance. So in order to use a high powered Magnifier, you would need to put your head very close to the object you are viewing. In addition, a Magnifier that is too powerful will distort the image making it difficult to read. Lastly, a high powered Magnifier has a very small viewing area. If you have too high a Magnification, it becomes difficult to use the Magnifier as you end up focusing on too small a part in the page. Donít get too caught up with Magification. Regretfully we are in an industry where some companies exaggerate Magnification. Buyer beware!
What types of Magnifiers are best for Needlepoint?Carson manufactures a number of Hands Free Magnifiers for crafting and needlepoint. They are often referred to as ďAround-the-NeckĒ Magnifiers because they are positioned just below the chest of the user and suspended by a cord around the user's neck. These "Around-the-Neck" Magnifiers provide the user with free use of both hands which is ideal for needlepoint. Caronís LumiCraft (model LC-15), MagniFree (model HF-25), MagniFree (model HF-15), and MagniShine (model HF-66), are all examples of "Around-the-Neck" Magnifiers. Visit Carsonís Hands Free Magnifier section.
Another type of Magnifier that is designed largely for crafts is the MagniCraft Magnifier (model MC-10). The MagniCraft has magnets that are embedded into this Bar Magnifier. This works very well for needlepoint patterns. The user can place the pattern on a metal stand. The Bar Magnifierís magnets will hold the pattern in place, and Magnify the appropriate line on the pattern. Visit the Sheet and Bar Magnifier section of this website to see all of our Carson's Bar Magnifiers.
What things should I consider when purchasing a Lighted Magnifier?Lighted Magnifiers come in a wide variety of styles and shapes. The most important consideration when purchasing a Lighted Magnifier is the type of lighting. Lighted Magnifiers come in LED and incandescent styles. Generally speaking a Lighted Magnifier with an incandescent bulb will be less expensive than an LED Lighted Magnifier. However, Lighted LED Magnifiers are generally brighter and use far less power than an incandescent bulb. When you consider the cost of batteries, LED Magnifiers are typically a cost-effective investment.
In recent years, Magnifiers have shrunk in size. Lighted LED Magnifiers are often powered by button-cell batteries, thus allowing for sleeker and more compact designs. Products that include Carsonís Lighted Rimless Magnifier and our Lighted MagRx could never have been made with out the use of LED Lights.
What are the advantages of Glass Magnifying lenses?Glass Magnifiers allow very high light transmission, which provides a very clear, precise image. Glass Magnifiers are also durable and extremely difficult to scratch. There are many grades of glass available, however the best grade of Glass Magnifying Lenses is better than the best grade of Acrylic Lenses. Glass Magnifiers typically Magnify slightly more than Acrylic Magnifiers as a result of the material density. The most popular Glass Magnifier from Carson is the SG-10 SureGrip Magnifier.
Glass Magnifiers have declined in popularity over the years. Twenty years ago, nearly all the Magnifiers sold in the US were made from Glass. Today, however, more than 90% of the Magnifiers sold in the US are made from Acrylic.