Originally Posted by stryder5
I am sceptical as this is a kind of advertising blurb
The erector tube also serves as the interface between the reticle and the adjustment knobs. It is here that the spindles and springs that lead back to the knobs make contact, and it is the erector tube that moves when you make your adjustments. Looking through the scope while adjusting the windage or elevation can be surprising to people. The reticle seems to move in the wrong direction. This happens because the image that arrives at the erector is actually upside down. When less elevation is dialed in the front of the erector tube is pushed down (compressing the erector spring) while the back pivots upwards, the reticle appears higher on the target. The barrel must be tilted downward to reacquire the target; this is where the reduction in elevation comes from. The exact opposite occurs when more elevation is dialed in. Windage works in a similar way, only in the horizontal rather than vertical plane. It is important to have a properly functioning erector spring to get the full range of adjustment. A cheap or worn spring can limit function at the upper end of travel.
So another view taken from the Internet.
My deben works as a cross between the two. I know this because I tried to take it apart to have a look at the turrets, and broke it.
The erector tube indeed pivots as per both examples. It is pushed against the turrets by a spring at 45 degrees (i think, cant quite see it yet inside). But there is a disc that contacts the surface of the erector tube, which has a thin pin and a bearing, so it can spin and not turn as you dial the turret above. However, due to the scope being turned to it's limit, the pin had bent, pushing the disc flat against the erector tube instead of just an edge touching as per the left hand example.
The issue i suspect was that springer recoil made the erector and disc lose contact for a moment, and because the disc could rotate, it could sit flat, or on an edge... leading to a slight difference in the erector tubes position, which lead to a zero shift... which while it held that position was constant throughout the ranges. But at ant given time (usually when the turret was under the least load) it could jump again, to another position.