Fantastic resource @FullMoonFever , thanks. I'll keep reading...

Fantastic resource @FullMoonFever , thanks. I'll keep reading further material, but can see how Purkinje imaging, scanning slit and Scheimpflug principle can all be applied in overcoming problems like this.

And of course, I hadn't quite thought of it like that: the lack of a need for an exact match actually allows for minor variations (even aside from constant tear film uniqueness) in image capture, as long as variations are still within the variance calculations that they're using.

Appreciate you posting on your weekend away too...enjoy your time relaxin'.