What is magnification? For the purpose of vision loss,
it is understood that magnification is that act of making something
appear larger so that it can be viewed more clearly. What is not
generally understood by consumers is what the different magnification
expressions mean.
You might have seen magnification expressed by a number followed by an “X” or the word “Times”. The “X” is simply a symbol that means “Times” and is often used to replace the word “Times” as it relates to magnification. For example; 2X and 2 times both indicate the same level of magnification.
You might also see vision aids use the word “Diopter” or “Dioptere” when expressing their products magnification. The number expressed in diopters is derived from the reciprocal of the focal length of the lens and is much more difficult for the average consumer to understand as it relates to the magnified size of the object. For that reason, most vision aids rely on expressing their magnification in units of “Times” and that is what we will focus on in this article.
The generally accepted measurement of “Times” magnification is a direct relationship to the measurement of the actual object size to the measurement of the apparent size of the object. For example; if you magnify a 1 inch tall letter 2X, it will appear to be 2 inches tall or 3 inches tall if it is magnified 3X. Though this is the generally accepted practice, there is no rule or standard that requires manufacturer’s to use this method, so it may be wise to check with a manufacturer before purchasing their product to make sure that you are getting the magnification that you are expecting.
How is magnification achieved? Magnification is achieved by choosing a focal area and expanding it. If you have ever used a magnifying glass, you have noticed that in the center of the lens, the focal area, the object looks bigger, and that around the edges of the lens, the object is distorted and smaller. The outer edges of the image have to be made smaller to make room for the larger image in the center.
A Video Magnifier expands the focal area onto a video screen. The magnification is controlled by the focal area of the Video Magnifier's camera and the size of the screen. There are two ways to increase the magnification of a Video Magnifier. Decreasing the focal area and then projecting the smaller area onto the video monitor makes the image look even larger though less of the object can be seen. A second method for increasing the magnification of a Video Magnifier is to increase the size of the video monitor. By increasing the size of the video monitor, you are taking the same focal area and stretching it out over a larger screen which produces a larger image.
While I am on the subject, I would like to address a common question that I am asked. Though it may seem obvious to some, it is an honest question that is asked by people trying to help as disabled family member that may have a hard time operating a Video Magnifier. Will a Video Magnifier display a whole page on the screen of video monitor? The answer is it can, but the magnification will either be very small or it may actually decrease the size of the print depending on the monitor size and the size of the page. Let’s say we are using a 20 inch monitor and the page height is 6 inches. A standard 20 inch monitor has a screen height of 12 inches. 12 divided by 6 is 2X magnification. 2X magnification will not come close to helping most individuals relying on a Video Magnifier. On the average, most people that ask this question estimate that approximately 20X magnification is needed. Using the 6 inch tall page and doing the math, 20 times 6inches is 120 inches or 10 feet tall. A 200 inch monitor would be needed to achieve a 10 foot tall image. So while I feel for these people and it is a perfectly understandable question, it is simply not possible at this time.
So know that you understand magnification, how do you determine what magnification is needed? A simple method for determining the minimum needed magnification is to determine the height of the letters of the smallest word that the user would need to read like on a newspaper or prescription and then determine the height of the letters of words that can be read normally with only glasses like the headlines of the newspaper or advertisement and then divide the larger number by the smaller number. The answer is the minimum magnification needed. If the example of the newspaper and the advertisement is not relevant, be resourceful. You can find different size print all around. You can even print out different size fonts from the computer or use pertinent objects.
Now that you now the approximate minimum magnification needed, you should know that people with Macular Degeneration and similar vision problems often times find their eyesight suddenly deteriorating. So you may want to choose a device that is capable of more than the minimum needed magnification, especially if purchasing a more expensive Video Magnifier.
That is about all there is to it. Magnification is how many times bigger the size of the original object is.
For more information, please see our other articles about vision loss and magnifiers or feel free to contact us.
Written and published by Tony Vaughn June 16th 2012
You might have seen magnification expressed by a number followed by an “X” or the word “Times”. The “X” is simply a symbol that means “Times” and is often used to replace the word “Times” as it relates to magnification. For example; 2X and 2 times both indicate the same level of magnification.
You might also see vision aids use the word “Diopter” or “Dioptere” when expressing their products magnification. The number expressed in diopters is derived from the reciprocal of the focal length of the lens and is much more difficult for the average consumer to understand as it relates to the magnified size of the object. For that reason, most vision aids rely on expressing their magnification in units of “Times” and that is what we will focus on in this article.
The generally accepted measurement of “Times” magnification is a direct relationship to the measurement of the actual object size to the measurement of the apparent size of the object. For example; if you magnify a 1 inch tall letter 2X, it will appear to be 2 inches tall or 3 inches tall if it is magnified 3X. Though this is the generally accepted practice, there is no rule or standard that requires manufacturer’s to use this method, so it may be wise to check with a manufacturer before purchasing their product to make sure that you are getting the magnification that you are expecting.
How is magnification achieved? Magnification is achieved by choosing a focal area and expanding it. If you have ever used a magnifying glass, you have noticed that in the center of the lens, the focal area, the object looks bigger, and that around the edges of the lens, the object is distorted and smaller. The outer edges of the image have to be made smaller to make room for the larger image in the center.
A Video Magnifier expands the focal area onto a video screen. The magnification is controlled by the focal area of the Video Magnifier's camera and the size of the screen. There are two ways to increase the magnification of a Video Magnifier. Decreasing the focal area and then projecting the smaller area onto the video monitor makes the image look even larger though less of the object can be seen. A second method for increasing the magnification of a Video Magnifier is to increase the size of the video monitor. By increasing the size of the video monitor, you are taking the same focal area and stretching it out over a larger screen which produces a larger image.
While I am on the subject, I would like to address a common question that I am asked. Though it may seem obvious to some, it is an honest question that is asked by people trying to help as disabled family member that may have a hard time operating a Video Magnifier. Will a Video Magnifier display a whole page on the screen of video monitor? The answer is it can, but the magnification will either be very small or it may actually decrease the size of the print depending on the monitor size and the size of the page. Let’s say we are using a 20 inch monitor and the page height is 6 inches. A standard 20 inch monitor has a screen height of 12 inches. 12 divided by 6 is 2X magnification. 2X magnification will not come close to helping most individuals relying on a Video Magnifier. On the average, most people that ask this question estimate that approximately 20X magnification is needed. Using the 6 inch tall page and doing the math, 20 times 6inches is 120 inches or 10 feet tall. A 200 inch monitor would be needed to achieve a 10 foot tall image. So while I feel for these people and it is a perfectly understandable question, it is simply not possible at this time.
So know that you understand magnification, how do you determine what magnification is needed? A simple method for determining the minimum needed magnification is to determine the height of the letters of the smallest word that the user would need to read like on a newspaper or prescription and then determine the height of the letters of words that can be read normally with only glasses like the headlines of the newspaper or advertisement and then divide the larger number by the smaller number. The answer is the minimum magnification needed. If the example of the newspaper and the advertisement is not relevant, be resourceful. You can find different size print all around. You can even print out different size fonts from the computer or use pertinent objects.
Now that you now the approximate minimum magnification needed, you should know that people with Macular Degeneration and similar vision problems often times find their eyesight suddenly deteriorating. So you may want to choose a device that is capable of more than the minimum needed magnification, especially if purchasing a more expensive Video Magnifier.
That is about all there is to it. Magnification is how many times bigger the size of the original object is.
For more information, please see our other articles about vision loss and magnifiers or feel free to contact us.
Written and published by Tony Vaughn June 16th 2012
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