After talking to a lot of people, I am now strongly gravitating towards a fixed 10 stop (ND3) filter.
At first, Schneider's Tru-Match Vari-ND
, that is based on a LEE filter holder with a 4x4" polarizer and a screw-on polarizer, seemed very interesting, albeit not cheap. However, further reading made me abandon this thought:
"Schneider True-Match Vari-ND Filter Disclaimer
Please note: An anomaly may occur when using a Variable ND filter when shooting wide angle (50mm and below) near to or at the highest ND point on the filter. The anomoly can be a very dark area in the center of the image, or an “X” pattern with lighter frame edges.
While all other manufactures only go up to a maximum of 8 stops Neutral Density, the Schneider Optics Vari-ND Filters boast a maximum of 11 stops ND. And because the anomaly only happens at the Max ND, no matter if the max of the filter is 6, 8, or 10 stops, that means when you use the Schneider Vari-ND filter at 8 stops, there is still no distortion in the image, where there would be in the competitor’s filter that maxes out at 8 stops.
For optimal performance, we always recommend using these filters on manual exposure. Vari-ND filters are best used for video capture at any aperture or wide aperture, high shutter speed still shooting.Schneider Optics does not recommend Vari-ND filters for smaller aperture, long exposure still shooting.