I have a Tiffen 85BN6 filter, and from what I've understood it's a combination filter of 85B + ND 0.6. Since the ND 0.6 removes 2 stops of light, and the 85B 2/3 stops, will the total light loss be 2+2/3 stop? Or is the idea with this filter that it for "simplicity" just removes 2 stops like an ordinary ND 0.6?