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 1 customers
Not a lot to say. Usual high Hoya quality. Does what it's supposed to do. I use it with Ilford SFX and Rollei IR film. Only problem and this is NOT the fault of design or build is that R72 filter are so dark that you have to compose & focus and then put the filter on. You will REALLY surprised how dark this filter is. Doing a series of shot starting with a filter factor of 16 (4 stops) is a good idea