The magnification of lenses is often specified in diopters or with the magnification factor. The higher a positive diopter number, the more the lens magnifies.
A simple formula can be used to convert diopters to magnification:
Magnification = (diopters/4) + 1
or vice versa
Diopters = (magnification - 1) x 4
| Diopters | Magnification | Percent | Focal length |
| 3 | 1.75x | 175 % | 33 cm |
| 5 | 2,25 fold | 225 % | 20 cm |
| 8 | 3 times | 300 % | 12.5 cm |
The focal length is also an important specification for the user. The object to be observed can only be optimally magnified if it is within the focal length.
The table above clearly shows that the focal length decreases as the diopter number increases. The distance to the object being viewed becomes shorter and the field of view correspondingly smaller. It should also be noted that at high magnifications, the distortion also increases.