Originally Posted by RobF
it's going to have to shift a lot pete... it's only 90mm to start with, to to great a 4mm change in radius, it's going to have to warp like liquorice
Yes OK, silly suggestion, but sometimes these problems are not the most obvious things like a problem with the scope..
It could be actually your eyes react differently, in different light & heat conditions, not the scope.
Probably another silly suggestion, but you get my drift.
Of course i'm taking a totally different solution to the problem, which I will test next year in GP season.