I'm loving this thread. How big is the Scharhosrt piece?
Depends on which one you're talking about
I've highlighted 5 of the parts in the below image and took the measurement of one of them. If you want something more specific, let me know.
Okay, I think I've got it sorted out. I started with the 49.72mm measurement that Sumatra so kindly provided and worked backwards from there, making sure to locate the sphere the correct distance in space relative from where the Scharhosrt piece would sit:
A closer look at the sphere roughed in for size:
I ended up with a diameter of 29.5715944, but considering things like rounding errors and lens distortion (and that I did this pretty quickly ), I'd call it 30mm.
I've included all of the metadata for people to look at the focal length of each shot.