4) Using the cursor over the 3D layout, estimate the YZ coordinate that, when aimed at from the object, will let the real ray reach the vertex of the stop or close to it. Do not worry about being precise.

5) Repeat the step 4) to determine the X coordinate with the Z rotation of the 3D layout set to +90, if the stop is also shifted in the X direction with respect to the paraxial entrance pupil (not for this sample file).

6) Set the Ray-aiming to “on” and enter the estimated X Y and Z (Z estimated – Z entrance pupil) values. If you set the Ray-aiming to "on" without specifying the pupil shift factors, you will get the "cannot determine object coordinates!" error as mentioned in the beginning of the article.

X= 0, Y= +30 and Z= 29.7 – 30 (close to zero so Z=0)

This sample case is only meant to demonstrate the use of pupil shift factor. In reality, the same system can be constructed with coordinate breaks and no Ray-aiming.