Jerry Bruzek wrote:
I purchased a set of 95mm Altura filters for my Sigma 150-600mm Contemporary lens and upon trying the circular polarizing filter, I notice that all my shots came out blurry. Figuring it was a cheap filter, I spent more for a GOBE polarizing filter but the results were the same. I also noticed that it was difficult to take the filter off. Is there a unique thredding for my lens which is not universal? I have not experienced this problem with any of my Canon ot Tamron lenses. Help!
Sorry to say Jerry but it sonds like operator error and that the focus is shifting as you rotate the polarizing filter. To test that focus, lock focus with gaffer tape and then rotate the polarizer. Verify focus and click.