This filtering system is actually quite bulky and looks very used to. But if one wants to use a neutral density filter, there is hardly an affordable alternative. Spin the horizon have always in the middle, I have never in my pictures the horizon in the middle. This can be the good setting and adjustment, works as desired. I find it a bit difficult to find the right course for this filter holder. The brochure was not as meaningful, as I had hoped. That's why only 4 stars.
