-21.00 in 1.74?

[Robert Martellaro]

Not saying it won't but eventually physical limitation comes into play, before you reach that limit chances are the manufacturers have set a software limit such as the -20, it might go higher but good design dictates leaving a buffer.

Sound advice. A poet once said...

You've got to know when to hold 'em
Know when to fold 'em
Know when to walk away
And know when to run

[sharpstick777]

Powers this high get complicated... 1) There are only a few people who can cast their own blanks so it give Quest an edge in 1.74. 2) most free-form generators max out at a -15.00 backside curve, which means either biconcave or a modified generator. 3) Software has to accommodate the higher powers, but its usually an edit to fix. 4) bi-concave or Free-form micro-lenticular are the best choices over a -15.00.