Question for you opti-types...

When you have a lens edged in a frame, I've been told that you should clock the front surface with the pins oriented vertically and then horizontally to determine warpage at the front surface. Is this the best way to do this? Obviously, I'm talking about single vision lenses here and not PALs. If so, what's the tolerance for warpage? 0.5D? 1D?

Any advice you can offer would be appreciated.

Dwayne