When we say -6D is the ideal spherical back curve, does that refer to a 1.53 index lens?
Printable View
When we say -6D is the ideal spherical back curve, does that refer to a 1.53 index lens?
That would be for any index. I try to strive for a -4 to a -6 while keeping in mind the frame's natural curve.
A back curve of -6.00 would have no reference to index. A -6.00 is a -6.00 period. The only time you would need to reference index is to determine what tool to use to arrive (surface) at a specified back curve from a given front curve if using anything other than a 1.530 index. For more info on ideal back curves you need to reference the old AO tillier lens design. Some of the older members.....I believe Mr Baker was an ex AO guy, could point you in the right direction.Quote:
Originally Posted by ravenclaw
This should answer most questions regarding ideal curves
https://www.2020mag.com/ce/evolution-of-single-vision