The dividing the filter factor into the ASA speed and setting the light meter with the resultant offfset seems like a good idea at first blush. Bt what do you do if you're shooting a snow scene, or adding a polarizer, working wih a ND filter, and have to adjust by different stops in addition to the contrast filter? Then for a second shot you take one filter off. Wouldn't it be easier to just leave the meter at box speed and adjust the stops on the camera after adding them all up?