If you're shooting video outdoors on a bright day with a DSLR or Mirrorless camera, chances are you're working with ND filters. ND Filters are essential to keep your shutter speeds down, while keeping your lens aperture wide open. One of the most annoying things of course is working with different lenses that each require different filter sizes and step up rings.
If you understand the frustration, then you'll be interested in checking out the new Fotodiox Vizelex ND Throttle Lens Mount Adapter. Instead of placing a variable ND filter on the front of the lens, the variable ND filter is actually built into the lens adapter (located behind the lens).
The first version of the Fotodiox Vizelex ND Throttle available is only for Canon EOS to Sony E Mount. Example compatible cameras listed are the Sony NEX-3, NEX-5, NEX-C3, NEX-5N, NEX-7, NEX-F3, NEX-5R, NEX-6, Sony NEX-VG10, NEX-VG20, NEX-VG30, NEX-VG900, NEX-FS100, NEX-FS700, NEX-EA50.
I don't see why a variable ND filter lens mount can't be made with M4/3 adapters, so hopefully that will follow up soon. Check out the product page for additional photos and specs for the new Fotodiox Vizelex ND Throttle (click here).
FotoDiox Vizelex Variable ND Throttle Canon EOS EF to Sony NEX E Mount Lens Adapter