I was thinking about this this morning. Assuming the figures we see on the Tele Vue website for field stops are real dimensions, and not effective/virtual, when they decided to make the 8mm Ethos, would they have to start with the requesite sized hole in lets say a piece of metal, that gives a 100 degree AFOV (lets assume no distortion) for an 8mm focal length - and then build around that?

Regards,

Rob.