Equal amounts of yellow and magenta equal neutral density as far as the paper is concerned. (Basically a graduated red,filtering both blue and green. ND filters of optical quality mounted on the lens is another possibility (most of us have one or two rolling around somewhere.

Sure, the proposed solution will work, but seems a lot of trouble to go to when there is built-in ND capability in the form of yellow/magenta filtration already.

Best,

Doremus

www.DoremusScudder.com