1、How to choose?
When matching glasses, when arrived to choose the link of Lens, Glasses Party is not at a loss? Do Not Know How to choose the Lens. Here’s how to choose the right lens for your degree.
2、The refractive index
The refractive index is the ratio of the propagation speed of light in vacuum to that of light in lens material.
The higher the refractive index, the thinner the Lens, that is, the same thickness of the center of the Lens, the same number of degrees of the same material Lens, the higher the refractive index than the lower the thickness of the Lens Edge. The higher the refractive index of the material, the stronger the ability to refract incident light.
At present, the main refractive index of lenses on the market are: 1.56,1.61,1.67,1.74.
Usually the first parameter many people come into contact with a lens is the refractive index. Then it is the most intuitive embodiment of the Lens is: The Higher The refractive index, the thinner the Lens.
For beauty and weight requirements, thin lenses are a good choice.
3、Abbe number
In choosing lenses, another key data term associated with lenses is abbe number. So what is the Abelian number?
Ernst Abbe number refers to the dispersion factor, which is used to measure the image sharpness of a lens. The higher the ABBE number, the smaller the dispersion, the clearer and more realistic the visual effect.
The human eye has an abbe number of 58.6, and the closer the Ernst Abbe number of the Lens, the more comfortable the lens will be.
4、Refractive index reference value
A, if the degree is 0-200 degrees, we recommend the use of 1.56 refractive index lenses.
B, if the degree in 200-350 degrees, we recommend the use of 1.61 refractive index lenses.
C, if the degree in 350-550 degrees, we recommend the use of 1.67 refractive index lenses.
D, if the degree of 550-800 degrees and more than 800 degrees, we recommend the use of 1.74 refractive index lenses.
5、Tips
If the pupil distance is too small, or the selected frame size is too large, it is recommended to increase the refractive index.
When choosing a frame, one should consider the interaction with the Lens:
The larger the frame size, the larger the diameter of the Lens, and the thicker the edges of the frame.
Do not think that the choice of a high refractive index Lens, make the edge of the glasses will be very thin, this is a mistake, because the same number of lenses made because the thickness of the pupil distance, astigmatism, axis, frame size and different.
Therefore, when we choose the lens suitable for our degree, we should consider all aspects, so that the glasses can be more comfortable to wear.
Post time: Jul-28-2021