While doing pictures we never think how to improve the quality of the pictures, because in first instance because nobody knows that there is something with the help of that you can improve it and the second may be because nowadays so many people taking photographs and many calling themselves photographer because of few successful pictures.

I found it very educating and in easy words explained the idea of using ND filters and when looking at the result that is obvious, with NF filters the result is much better. Of course it is understandable that there are many other grading of them but for those who would like to do something with their pictures like offering their service or selling they need to know that and I think it is great that you are doing such tutorial :)