2 MAGNIFIERS ALL RIGHTS RESERVED © BI-CONVEX LENSES The two lens surfaces are symmetrical, giving a medium magnification at the centre of the lens. ASPHERICAL LENSES One surface is more curved than the other. This allows good magnification without any distortion at the edges and with a large visual field. It is the best lightweight lens for magnification. PLANO-CONVEX LENSES The deep curvature of these lenses results in a high magnification and a good visual field. APLANATIC LENSES They are composed of two plano-convex lenses. The magnification is very good, without any distortion and with a large visual field. These lenses are heavier, thicker but in return they give the best quality. ACHROMATIC LENSES They are composed of a positive Crown glass lens and a negative Flint glass lens and have a high magnification. They correct vision on various wave lengths and thus reduce the chromatic aberration. lens diameter lens size package weight view angle focal distance Ø International Standard D= Magnification x 4 D= Magnification (x 4)-4 Magnification (D:4) Magnification (D:4)+1 Diopters (D) 4D 6D 7D 8D 10D 12D 15D 16D 20D 24D 28D 31D 32D 36D 40D 44D 48D 52D 56D 60D 76D 1X 1,5X 1,75X 2X 2,5X 3X 3,75X 4X 5X 6X 7X 7,75X 8X 9X 10X 11X 12X 13X 14X 15X 19X 2X 2,5X 2,75X 3X 3,5X 4X 4,75X 5X 6X 7X 8X 8,75X 9X 10X 11X 12X 13X 14X 15X 16X 20X