I use the adapter ring around my polarizing filter, I am Tamron SP AF 17-50mm 2.8 XR Di II LD Asp IF like to use to be able to use 100mm 2.8 Macro USM also the Canon EF. The adapter is made accurately, screw on and off goes smoothly forward. The low pitch of the filter thread makes in rare cases for tilted positioning, which is not but is on the adapter. All in all a recommended investment if you do not like to purchase each filter several times. The lens belonging to cover course no longer fits with mounted adapter + filter)