The filter has the same thread pitch as any other standard photo filter. 

You can of course choose shorter exposure times because of the open aperture, which may be an advantage in the shade, in the evening or in dark corners, especially if you are taking photos without a tripod. Where desired, the bokeh is also a dream. The depth of field can really play off best in strong foreground-background contrasts, such as in portraits. It's possible that the crop factor, e.g. with small format cameras like my 550 D, ensures that you get a slight telephoto effect, i.e. you might not get a complete sky on it at all. 

But! ^^ My God, what are these for .... Just take it with 35mm wide, it fits. Or in high format, take 10 pictures that overlap 20% and add it up (Panorama Free google), then you have a landscape with depth of field. 

Front threads are available, allowing another filter to be attached to it, as long as it has the same aperture 

There is a front thread to allow another filter to be mounted in front of the Black Soft filter, as long as the larger one is of the same aperture. For example, if the filter is 67mm, you would need to mount a 72mm filter.