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Measuring magnification

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/30/2008 at 23:21
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How to Measure magnification
How can I see how strong a magnifying glass is?


I bought this magnifying glass http://www.liangdianup.com/inventory/189901.htm and I want

to know how to test it to see how strong it is. I hear a lot of people talk about

magnifying and how strong the magnification is, but I would like to know the true

magnification of my magnifying glass. I have a few of them and some seem stronger then

others. How can I rate these? How can I pin a correct number on mine? How do the companies

that make these come up with these numbers.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 03:26
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Determining magnification: The power of an eyepiece is found by dividing the focal length of your telescope by the focal length of the eyepiece. For example, a 20mm eyepiece on a 2000mm telescope (2000 ¸ 20) gives you 100 power (100x). This makes objects appear 100 times closer to you through the telescope than they appear to your unaided eye. The same 20mm eyepiece on a 1000mm focal length scope (1000 ¸ 20) gives you 50x. The longer the telescope focal length, or the shorter the eyepiece focal length, the higher the power – but the dimmer the image.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 03:34
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The Mathematics of Lenses

Ray diagrams can be used to determine the image location, size, orientation and type of image formed of objects when placed at a given location in front of a lens. The use of these diagrams were demonstrated earlier in Lesson 5 for both converging and diverging lenses. Ray diagrams provide useful information about object-image relationships, yet fail to provide the information in a quantitative form. While a ray diagram may help one determine the approximate location and size of the image, it will not provide numerical information about image distance and image size. To obtain this type of numerical information, it is necessary to use the Lens Equation and the Magnification Equation. The lens equation expresses the quantitative relationship between the object distance (do), the image distance (di), and the focal length (f). The equation is stated as follows:

The magnification equation relates the ratio of the image distance and object distance to the ratio of the image height (hi) and object height (ho). The magnification equation is stated as follows:

These two equations can be combined to yield information about the image distance and image height if the object distance, object height, and focal length are known.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 03:50
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So from the above it would appear that when we talk about the magnification bringing the object closer it is in fact mathematically correct. If the magnification is 10x we say the object is brought 10x closer so that a 100yd object appears to be at 10yds.
So if the object you are looking at is 20 inches away and the image is being formed on the other side of the lens at say 8 inches, then the magnification is 1:0.4 0r 2.5 times.
As far as i know you can detrmine the focal point (where the image is being formed) by holding a light source(lamp, candle) at a known distance (say 1yd) and thenholding the lens up. Take a cardboard and move it backwards and forwards untill a sharp lightspot is formed. Measure the distance to the cardboard, say you get 6inches. The magnification is 6/36=1:0.16 or 6.25X 
Now you can take all your magnifying glasses and the one with the shortest focal point has the most magnification.
 
 


Edited by 8shots - December/01/2008 at 04:17
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 04:01
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The highest magnifying power is obtained by putting the lens very close to the eye and moving the eye and the lens together to obtain the best focus. The object will then typically also be close to the lens. The magnifying power obtained in this condition is MP0=¼Φ+1, where Φ is the optical power in dioptres, and the factor of ¼ comes from the assumed distance to the near point. This value of the magnifying power is the one normally used to characterize magnifiers. It is typically denoted "m×", where m=MP0. This is sometimes called the total power of the magnifier (again, not to be confused with optical power).

Magnifiers are not always used as described above, however. It is much more comfortable to put the magnifier close to the object (one focal length away). The eye can then be a larger distance away, and a good image can be obtained very easily; the focus is not very sensitive to the eye's exact position. The magnifying power in this case is roughly MP=¼Φ.

A typical magnifying glass might have a focal length of 25 cm, corresponding to an optical power of 4 dioptres. Such a magnifier would be sold as a "2×" magnifier. In actual use, an observer with "typical" eyes would obtain a magnifying power between 1 and 2, depending on where lens is held. An older person might obtain an actual magnifying power of 8 or more with this lens, however, due to the eye's longer near point distance.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 04:03
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I hope you are very confused by now!!!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 12:46
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/01/2008 at 17:57
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You've out done yourself "8", heres your reward Star
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/02/2008 at 00:45
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Originally posted by Ed Connelly Ed Connelly wrote:

 
Laugh Above Maybe she needs a magnifying glass to see those split ends!


Edited by 8shots - December/02/2008 at 00:46
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/02/2008 at 05:48
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                                                                                                          Big Grin
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/02/2008 at 12:40
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WOW............I've read this twice and now I know nothing, but Thank you 8shot for the info interesting reading and I did learn from that post Thank you again
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