How do you get a 200mm erector assembly in a 34mm tube?Lets say you have a scope with 3m elevation adjustment at 100m. This gives you an angle of about 1.7° from top to bottom.
I don't know how long the typical erector system is but lets just say 200mm. In that case the erector would be moved about 6mm in height, from top to bottom. (Edit: That is a very simple calculation leaving out many factors, so nothing more than an a approximation. For a 150mm erector it would be 4,5mm of total travel)