No a sonnar f1.5 is not the rarest I can find them under$100 sometimes but that one is a disaster. Repair people I've used several over the years 2 of which have very expensive reputations I don't want to condem any repair people in this forum. Who would be your suggest? So if I buy the latest greatest version of a leica M mount I should have no worries 50 years from now if I make it the long?