Which ND Filter for GH4 + Canon Lenses?

[duarted]

Hello

I have the Panasonic GH4 and I'm using it with the Metabones Speedbooster for Canon lenses.

This means that if I'm shooting in a place where there's too much light, everything it's going to be too much white because the maximum aperture of the Gh4 is f/14

Since I'm shooting a lot in the Caribbean with a lot of sunlight I need ND filters for my lenses.

Oh and I use it only for Video so that's the reason why I need the ND filter

Can someone recommend me ND filters? I'm not sure how many f.stops should I look for.

My lenses are:

- Canon 17-40mm f/4 (77mm)
- Canon 24-105mm f/4 (77mm)
- Canon 70-300mm f/4 - 5.6 (58mm)
- Canon 50mm f/1.8 (52mm)

PS: I had a variable ND filter (cheap) but I didn't like the quality of the video when I was using it. But I guess a good Variable ND filter would be the best option for video?
Thank you!