Hi Greg, Thanks for the reply. Lens is working much better now. I should have added that I was making a repair to the lens, replacing a ribbon cable and the mounting ring after it had been dropped and broken. What I eventually found was that the ribbon cable was fouling the movement of the rear lens element (restricting its movement by only about 1mm) and that was causing the focussing issues. After tucking the ribbon out of the way the situation was much improved. Close focussing distance is as specified 0.9m at both ends of the zoom although there is still a slight focus change when zooming, nothing like as bad as it was though. Really happy with the repair, soldering was very tricky though and I can recommend Luton Cameras in the UK for the parts which only cost £15. Steve.