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microscopes | magnification, diopter & focal length
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Comparison of Magnifying Power, Diopter & Focal Length
Lens curvature controls magnification and focal distance. Magnification is sometimes measured in diopters which are defined as the reciprocal of the focal length of the lens in meters. (diopters = focal length divided into 1)
1 diopter = 1 / 1 meter
The power listed in the following chart was calculated according to the standard procedure of adding one to the quotient of the number of diopters divided by 4. (Power = 1 + (diopters/4))
8X Power = 1 + (28 diopters / 4)
| Power* | Diopter | Focal Length |
|---|
| | | inches |
| 1.25 | 1 | 39.37 |
| 1.50 | 2 | 19.69 |
| 1.75 | 3 | 13.12 |
| 2.00 | 4 | 9.84 |
| 2.25 | 5 | 7.87 |
| 2.50 | 6 | 6.56 |
| 2.75 | 7 | 5.62 |
| 3.00 | 8 | 4.92 |
| 3.25 | 9 | 4.37 |
| 3.50 | 10 | 3.94 |
| 3.75 | 11 | 3.58 |
| 4.00 | 12 | 3.28 |
| 4.25 | 13 | 3.03 |
| 4.50 | 14 | 2.81 |
| 4.75 | 15 | 2.62 |
| 5.00 | 16 | 2.46 |
| 5.25 | 17 | 2.32 |
| 5.50 | 18 | 2.19 |
| 5.75 | 19 | 2.07 |
| 6.00 | 20 | 1.97 |
| 6.25 | 21 | 1.87 |
| 6.50 | 22 | 1.79 |
| 6.75 | 23 | 1.71 |
| 7.00 | 24 | 1.64 |
| 7.25 | 25 | 1.57 |
| 7.50 | 26 | 1.51 |
| 7.75 | 27 | 1.46 |
| 8.00 | 28 | 1.41 |
| 8.25 | 29 | 1.36 |
| 8.50 | 30 | 1.31 |
| 8.75 | 31 | 1.27 |
| 9.00 | 32 | 1.23 |
| 9.25 | 33 | 1.19 |
| 9.50 | 34 | 1.16 |
| 9.75 | 35 | 1.12 |
| 10.0 | 36 | 1.09 |
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* Some manufacturers determine power more conservatively by dividing diopters by 4, so a 28 diopter magnifier would have a power of 7.
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