I'll have to get back to you later. Our website went offline overnight - so people are busy working on that.
Feels like I can get back to you on Monday.
Feedback from the engineer for your model Steve:
The calculator is correct. It could use more significant figures, the divergences is not really 0 but everything looks okay.
Negative focal length lenses are allowed.
Hi there. I noticed the spike in traffic from this thread to our beam propagation tool. This other lens design tool may be more useful for you.
https://lightmachinery.com/optical-design-center/lens-design-cloud/
Have fun -
Gregg @ LM