duto and hot mirror filters

[divewizard]

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?

[JHutchins]

Originally Posted by divewizard

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?

It's an infrared blocking filter and useful if you have a Leica M8 or other digital camera with an inadequate IR blocking filter over the sensor.