I have lots of filters given to me by my father and recently I have been experimenting with alot of them. I have been reading in the forum about a neutral gradient filter or ND filter.
What is the main purpose of this kind of filter and how does it compare to a polarizer? Also what kind of markings would be on the filter to identify it? I have over 20 filters (some duplicates) that my father gave to me and I am trying to figure out what they are and how best to use them.
Thanks for all your help!