Drop in Vari ND filter for RF mount

[Dholai]

Does Canon or any of the 3rd parties have a drop in Vari ND filter for long leses? I could not find one. The EF-RF adapter's Vari ND does not fit the RF lens' slot. I need one for my 400/2.8 RF .
Please guide me

 

[neuroanatomist]

I’m not aware of one ever being made for the supertele lenses. It would have to be built like the CPL with geared rotation.

You can use single density filters, either gelatin in the holder that comes with the lens or 52mm threaded with the separately-purchased holder for those.

 

[Dholai]

Thank You. I gave up.