Rendererclear=0 Problems with Alpha interpolation (fadeout)

What I want to is to slowly fadeout a renderer to black, with clearmode set to 0. I’m using a black Quad with Alpha set to 0.004, but the fadeout stops at a certain amount of lightness, it’s not getting black at all. I can understand why this is happening but can’t find another way, I tried different blendmodes, too.

If your using dx9 set the texture format to a higher bit depth, 16 or 32 bit per pixel, alternately add an lfo to the alpha and modulate it slightly to clean up every now and then.
Also if your using colour nodes, use Rgb not Hsl