I managed to balance GH5 and Sigma 18-35 with ND filter on old Moza Air gimbal and it works smooth and steady, just saved a lot of money Weebill S would cost
Rent a Sigma 18-35mm f/1.8 DC HSM Art EF Mount + Variable ND Filter, Best Prices | ShareGrid New York, NY
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Amazon.com : 72mm Variable Neutral Density NDX Filter for Sigma 18-35mm F1.8 DC HSM Macro : Electronics