Summary: Polarization was fine but the construction bothered me (could be just the one I received). I found the adjustment ring really loose and it would move without being touched. Also, the outer ring didn't appear to have a "mark" for easy location. I exchanged this filter for the Hoya Multi-Coated CP and found it to be better constructed.
Summary: Took it out for a end of summer outing on the lake. Did very well with the sky and water and brought out the fall colors. This makes subtle effects so they look more natural than some polarizers I've used The first one I received had spots on it, and I had to return it.
Summary: The Tiffen HT Circular Polarizer has a much subtler effect on my photos than I have experienced with polarizers from other manufacturers. The fact that it transmits more of the available light reduces the extreme color saturation you get with other circular polarizers which may reduce your exposure by as much as two stops. This keeps my exposures much truer to the natural color which is always desirable. An expensive product to be sure, but you do get what you pay for.
Pros: Clear Optics, Consistent Effect, Easy to clean, Strong Construction
Summary: Use it to darken blue skies and cut reflections on leaves. It really darkens the blue skies haven't had to use it yet to cut reflections. If you are not careful the skies can get really dark. Have to use it more to get used to it. So far I like it and it does the job it's supposed to.
Pros: Clear Optics, Consistent Effect, Firm Mount, Strong Construction
Summary: This product has improved the saturation and depth of my pictures already. Looking back on the photos I took without it I can see the washed out look that could have been so much better. It fits easily on my lens and is easily stored in the case. It stays in the camera case at all times.