thanks for the heads up.
so my lens thread size is as follows
35mm - filter size 52mm
18-105mm - 67mm
17-50mm filter size - 72mm
11-16mm - filter size 77mm
seems that a 62-77mm step up ring would be more appropriate, pls correct me if i am wrong.
u will need 3 step up ring.
52-77
67-77
72-77
if u dun intend to use all 3 lens for your ND filter, just get the one u need.
otherwise u can consider the Lee Big stopper, just get a square filter, one size fits all.