What is meant by the joint luminosity range of lenses

The combined lens photometric range is the sum of the absolute values of the spherical and cylindrical lenses of a lens.

The spherical lens (SPH) is the degree of myopia, hyperopia and presbyopia.SPH is "-" for myopia; SPH is "+" for hyperopia or presbyopia. Spherical lenses have concave and convex lenses, concave lenses are indicated by the "-" sign to correct myopia; convex lenses are indicated by "+"; to correct hyperopia. Column lens (CYL) is the degree of astigmatism.

Extended information

Lenses can be divided into spherical lenses, aspheric lenses according to the surface processing.

1, spherical lenses

Spherical lenses, the two sides of the lens was a spherical curvature, when different wavelengths of light, with parallel optical axis incident on the back of the lens in different locations, in the plane can not be focused into a point, and the formation of aberration, affecting the image of the problem, the periphery of the lens to see the object has a distorted phenomenon, which restricts the wearer's field of vision.

2, aspheric lenses

Aspheric lenses its surface curvature is different from ordinary spherical lenses, in order to pursue the thinness of the lens will need to change the curved surface of the lens, the previous spherical design, aspheric design, to correct the image, to solve the problem of distortion of the field of vision, and at the same time, to make the lenses lighter, thinner, more flat. Moreover, it still maintains excellent impact resistance, making it safe for wearers to use.

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