You can use a circular polarizing filter on the Tamron 15-30. I do. But, you have to have a very large filter adapter and use large 150X150 polarizing filters. I use the NISI adapter and it works fine with both the polarizer, neutral density and graduated neutral density. It's not cheap, but it works well. They also make one for the Nikon 19mm tilt shift.
Nikon
You can use a circular polarizing filter on the Tamron 15-30. I do. But, you have to have a very large filter adapter and use large 150X150 polarizing filters. I use the NISI adapter and it works fine with both the polarizer, neutral density and graduated neutral density. It's not cheap, but it works well. They also make one for the Nikon 19mm tilt shift.