Amazon.com : Polaroid Optics 52mm Neutral Density Filter [ND 0.9] Compatible w/ All Popular Camera Lens Models : Camera Lens Neutral Density Filters : Electronics
Amazon.com : Polaroid Optics 52mm Neutral Density Filter [ND 0.9] Compatible w/ All Popular Camera Lens Models : Camera Lens Neutral Density Filters : Electronics
How to make a film pack ND filter for your Polaroid SX-70 – Angie Muldowney