Hey Tunde, I use screw in filters(55mm) for my camera and it does gives a lot more options.   I know there are some camera mods that use clear glass to replace the hot mirror but you do end up with the added expense of the external filters.  I have purchased a Hoya R72, Tiffen 87, and a Tiffen hot mirror for a total of about $180(US), but I was crazy enough to do the camera mod myself and saved that expense.  But look what I get, pink watermelon seeds.  I am also thinking about a UV pass filter to see what that produces.

Mike