1.70

[autumnehiver]

any input on 1.70 vision-ease thindex vs. same index by hoya? seem to be the only two companies making this index? is hoya's higher cost justified?
thanks.

[Uncle Fester]

Welcome aboard the Optiboard!!!

I believe the only difference between a 1.70 and a more common 1.71 is the laser used in the photo-spectrometer used to establish the index of refraction. One is sodium the other helium?

Europe tends to use one the USA another.

Am I correct???

I tend towards "lab choice" as we are heavily managed care and haven't really heard a great deal of sentiment towards brands.

[Uncle Fester]

I think it's basically a juiced up 1.67 (by adding more sulfur?) by Mitsui Resins where most of the resins come from to make high index lenses.

http://www.mitsuichem.com/special/mr/about/

[autumnehiver]

yes, but both hoya and vision-ease advertise these as 1.70. which one do you refer to as 1.71?

[RT]

Many years ago, Hoya marketing a material called TESLALID with IR of 1.71. That material was discontinued in favor of the current 1.70 EYRY. That's where the confusion about 1.71/1.70 comes from.

As compared to other high index products, 1.70 has a higher Abbe value (36) and can be surfaced as thin as 1.0 center thickness when combined with one of Hoya's AR coats. Actual center thickness depends upon your lab's surfacing and coating processes and could vary depending upon who your lab is.

[autumnehiver]

right, so the different 1.70 lenses (i'm only aware of hoya and vision-ease thindex) have exact same properties with no preference either way? it seems that hoya is always highest cost.

[Lelarep]

The only way they have the same properties (Identical) is if they come from the same chem. company. Otherwise there have to be differences, since otherwise there would be lawsuits, etc...

[Tallboy]

Hoyas AR is better. Thats about it. The Thindex is great when a low cost High ABBE stock lens for a High minus is needed.