Removing black spot in Mental Ray’s Final gather
Black spot removal in Mental ray renders
You can download the sample scene in 3ds max 9 format of a light fitting which demonstrates the problem of the black spot appearance that occurs when you final gather the mental ray render.
Black Spots can be seen in this render

Black Spots removed using DL3D shader

Final image rendered with Mental Ray 3ds max 9

Black Spot Removal in mental ray’s final gather