Until recently, filtering the Panasonic AG-3DA1 was a challenge. Basically you had to use a 6×6 mattebox with a sliding base plate, or engineer a smaller mattebox to fit the housing for the lenses. Neither option was optimal given the small and compact nature of this camera.
As far as filtration, I found that using ND filters on the 3DA1 is a must. The camera handles interiors well, but after you open to your widest stop, the camera starts increasing gain to raise luminance levels. Exterior daylight shots will definitely need an ND, so having a set of straight NDs and a set of grad NDs would come in handy. Watch my video above for more on this mattebox setup for the 3DA1.