Niall Cullinane

I was always told to place the hot mirror at the front if you are using more then one filter to reduce reflections between the filters. If you are using a hot mirror ND combo you should have the shiny side facing out. If you need to use two NDs only one should be a HM/ND combo. The second should be a straight ND. Most combo sets I've used have a 1.2, sometimes higher. Otherwise you're probably going to need a set of straight NDs as well. Alot of DPs I've worked for have found that they lose around a 1/3 of a stop with the hot mirror. Has anyone here found that? Niall