HOYA UV-IR filters.
These are specialized filters that cut BOTH UV rays below 390nm and IR rays above 700nm. This is important because the visible spectrum is between 400-700nm. Basically UV rays and IR rays both can diminish image clarity and sharpness. But by blocking them both before they get to the image sensor there is a noticeable increase in image quality.
Reviewed by 3 customers
This is probably the most fun filter I own. I can choose to make trees pink or foliage white, depending; and it's an incredibly easy process! I have to say though, it takes a bit to learn how to focus first and mount the filter second, but it's worth it! Great buy!
I used the product with a Fuji Pro S3 and Nikon Lenses... this filter works with slightly less dramatic effect (which I find more pleasing) than I received with B+W infrared filters on other Nikon Products.