On a bright sunny day I did some tests using the Variable ND Freewell Filter from copter.eu. You can probably get it elsewhere as well. Sadly the variable settings on the the filter are not easily transposed in to ND values but the important point is that as shown in other videos on the forum when the Typhoon camera tilts up and down the automatic gain on the camera comes in to action in Auto mode. It is not unmanageable but there is a definite change of exposure when looking down as opposed to showing the horizon. I hope that I will get used to different filter positions for different weather conditions.