Higher indices' effects on edge thickness

[drk]

This is bothering me, because I'm sure the answer is simple:

Will the differences in edge thickness between materials of different indices be more pronounced in higher powers?

In other words,

If the difference in edge thickness between 1.5 and 1.6 with a 70mm blank is 1mm at -4.00, will the difference be 2 mm at -8.00? Or will the difference still be 1mm at any power?

What would the equation to calculate ET be? I know the variables could be radius of lens, index, center thickness, and possibly power.
ET=CT+ F x n ?

I'm too pressed to look this up.

The bottom line to me is: is thinning by using high indices more pronounced at higher powers, or is the effect independent of lens power?

[shanbaum]

Will the differences in edge thickness between materials of different indices be more pronounced in higher powers?

Yes, and it's non-linear. The thickness difference increases, and the rate at which it increases relative to power increases. Here's an example for a centered 50mm round lens with a flat front, comparing 1.498 and 1.596 indices:

power edge thk difference

-2.00 ----- 0.2
-4.00 ----- 0.4
-6.00 ----- 0.6
-8.00 ----- 0.9
-10.00 ---- 1.2
-12.00 ---- 1.6

Increasing the diameter would also increase the rate at which the difference increases.

[drk]

Nice response, Shanbaum. Thank you.

[drk]

Yes, and it's non-linear. The thickness difference increases, and the rate at which it increases relative to power increases. Here's an example for a centered 50mm round lens with a flat front, comparing 1.498 and 1.596 indices:

power edge thk difference

-2.00 ----- 0.2
-4.00 ----- 0.4
-6.00 ----- 0.6
-8.00 ----- 0.9
-10.00 ---- 1.2
-12.00 ---- 1.6

Increasing the diameter would also increase the rate at which the difference increases.

I thought I'd look at the rate of change in your example
power edge thk difference rate of change
-2.00 ----- 0.2
-4.00 ----- 0.4 (0.1mm/D)
-6.00 ----- 0.6 (0.1mm/D)
-8.00 ----- 0.9 (0.15mm/D)
-10.00 ---- 1.2 (0.15mm/D)
-12.00 ---- 1.6 (0.2mm/D)