Rent a 77mm ND Filter 0.9 (3 stops) at TheLensDepot.com
Variable ND Filter ND2 to ND400 neutral density filter Multi Coated - K&F Concept
77mm Indie Pro Infrared/Neutral Density Filter Kit - W77INDPROKT – The Tiffen Company
Tiffen 77mm ND 0.6 Filter (2-Stop) 77ND6 B&H Photo Video
Amazon.com : K&F Concept 77mm Variable ND Filter ND2-ND32 Camera Lens Filter (1-5 Stops) No X Cross HD Neutral Density Filter with 28 Multi-Layer Coatings Waterproof : Electronics
K&F Concept 77mm Variable ND Filter - Acme Camera Co.