The panto that is used to compensate the design is to me better thought of as the angle the lens makes with the visual axis, not the angle it makes with the plane perpendicular to the floor. So as the head moves so to does the eye's and glasses in a stationary group of objects. The angle compared to the plane perpendicualr to the floor will change, but the glasses will remain relatively stationary in front of the eyes
I think your point here is valid, I am not sure that most opticians are more than capable but a select few are and those are the ones that tend to visit this board so we are lulled into a sense of greater opticians out there as the norm. Manufacturers have taken this varying degree of education and skill into account though, the lenses can be ordered with vertex, panto, and faceform or not, the accurate measures optimize the design to the pateints particular situation. Without these measurements "averages" are used to create the lens. Every lens from the traditional molded designs to the freeform make assumptions that the lens will have a certain degree of tilt panto and faceform and they are designed for a certain vertex distance. Even single vision designs are designed for a certain vertex distance.
Same issues here the measurements can be off from a little to a significant, the reason why more equipment and measureing tools keep coming out. These lenses are the creme of the crop, this is not conjecture but a majority of PAL non adapts coem from wrong measurements PDs and seg hgts. Throw in additional measures and you have a point that issues may coem up, but again keep in ind these lenses are not your average ordinary lenses.
Although the angle the lens makes with the visual axis is fixed the angle the lens makes with the plane perpendicular to the ground is not fixed and this can and does cause error. While their is room to improve the measureing device education for the measurer is far more simple IMO. However, the march for improved measureing devices moves forward.
I think when it comes to opinionated I will have to defend my throne, but you can be prince if that suits you. Darryl has opinions and you have opinions but when it coems to facts they are just that, facts. I would say Darryl is one of the great optical minds in our country and his ability to share the most complicated subject while trying to avoid bruising ego's is a real show of class.
Personally, I wouldn't beat you up until after we had a few pints. ;):cheers:
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