in any case, my friend bought my present from www.lens.sg
i'm recommending it because... nowhere else do I know you can find so many manual focus lenses... their shop front is now at peninsular, the shop with a blank white signboard in the corner, excellent service and patience to let you try the lenses out.
apart from not knowing how to correct distortion, my friend dropped my camera bag.
my tamron 17-50 ended up with an unacceptably stiff zoom ring... recently brought it to Steven @ Camera Hospital... the zoom ring is damaged... and the part which records distance information and sends it to a hotshoe flash is broken... his assessment is that it is not worth repairing... just let it die a slow death... then upgrade...
you have served me well even though i often despised your image output.