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發表於 2015-10-30 14:14:32
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Found this on the Internet, good reference... it is 1.74, not 1.71. 
Plastic High Index Lenses Thickness Guide
1.61 index lenses are approx. 25% thinner than 1.5 index lenses
1.67 index lenses are approx. 40% thinner than 1.5 index lenses
1.74 index lenses are approx. 55% thinner than 1.5 index lenses
In addition to the above Double Aspheric lenses (Bi Aspheric) are flatter than standard High Index Plastic (single aspheric) lenses, so there is less curvature is the lens. This results in a flatter design hence makes the lenses approx. 10% thinner in all lens indexes.
1.61 index Double aspheric lenses are approx. 35% thinner than 1.5 index lenses
1.67 index Double aspheric lenses are approx. 50% thinner than 1.5 index lenses
1.74 index Double aspheric lenses are approx. 65% thinner than 1.5 index lenses
Glass High Index Lenses Thickness Guide
1.7 index lenses are approx. 50% thinner than 1.5 index lenses
1.8 index lenses are approx. 65% thinner than 1.5 index lenses
1.9 index lenses are approx. 80% thinner than 1.5 index lenses
If you are short sighted (near) and have a strong “-“ prescription, the thinnest lenses available are Glass 1.9 index lenses.
If you are long sighted (far) and have a strong “+“ prescription, the thinnest lenses available are Plastic 1.74 index Double aspheric lenses. |
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發表於 2014-9-11 15:36:54