Hi,

We have just acquired a surfacing lab, nothing too hi tech, generator is capable of cutting to -13D

I managed today to work a -16D by first working the front surface concave.

Another job is floating about needs a -20 (with some cyl) and if i order this in it will cost approx £30, is working the front to -7 optically acceptable or will it throw up problems for the Px.

What are peoples views on this? Are there limits, should it never be done, is it OK?

Regards,
Rick