Dan, I am modeling ( just as a learning ex) the 90 degree wide angle prescription on the OpticalRayTracer3.2.jar
The model is predicting an on axis focal length of about 98 mm and the optimum increases to about 110 mm at about 35 degrees off axis ( ie 70 degrees coverage).
But I am not sure If i read the prescription correctly, in the 12.6 mm distance between the lenses.
Do you know if that distance is between glass to glass on the axis , or were some other reference datum used in the lenses?
What frame size would this lens have been intended for?
What does "no dioptre diaphragme :2 " mean?

Thanks!