duto and hot mirror filters
I recently bought a batch of 82mm filters, many step-down rings, and 82mm lens caps from Craig's List for $120 becasue it contained Hoya HMC ND8, ND4, ND2, circular & linear polarizers that I wanted to use with my Pentax 6x7.
It also contained a Hoya Duto filter and a Tiffen Hot Mirror filter. Although I think I know what a Duto filter is for, I don't have a reason at the moment to use it. Why would I want to use this filter?
The Hot Mirror filter I have even less idea why I might use that. What use is it?