Excellent article!
ruraldoc, I think you may have some of the answer. I also think that some of the 30mm tubes allow the makers to put whatever is holding the glass in place further away from the center of the glass, giving a bit wider space for light, glass and coatings to do their thing.
JMHO.
I'm not sure some of the 30mm erector systems are actually larger than 1" erector systems, just more room for adjustments/more elevation for LR shooting.
Comments on that are welcomed.
DF
