in another thread here, <(Novoflex ) i have been advised to use english. my experience with the minolta 90mm wa not that positive. better than my old tele-elmarit, but the plane rear element gave undesirable reflections back to to the sensor. so i gave up and traded it as part payment towards an R9.
As for my comments to the 800mm above, I still feel is must have been difficult to shorten the lens in order to fit the R -mount. especially since the minolta needs an intricate system for fitting the obligatory rear filters. It seems that Minolta also specified a specific glass type for the iflters.
p.