Make sure your filter is set between the Min and Max marks. Adjust your focal length and your position and then reduce the ND’s density value by rotating the ring towards the Min mark until the pattern disappears.
Because there are so many combinations of cameras, lenses, sensors, and other factors, it is very hard to predict which circumstances will create the x-effect. The x-pattern is usually caused by rotating your variable ND filter past its maximum setting. Using a variable ND with a wide-angle lens can increase your chances of encountering an x-pattern. The ND2-400 has limited application with wide angle lenses because the field of view is so broad. The filter can only be rotated about halfway along the Min to Max range without encountering the x-pattern – you can thank physics for this restriction. Variable ND filters consist of two polarizing filters, which can cause issues because the polarizing effect varies so much across the broad field of view of wide-angle lenses. For this reason, we recommend using fixed ND filters, or Variable ND2-32 or ND8-128 with wide-angle lenses, and suggest you avoid stacking filters to avoid any vignetting.