Sorry if the question sounds a little odd. I recently dug out my Hoya NDX8 from hibernating in the drycabinet and noticed that it gave a very strange green cast, something which I did not notice when I used it in the past. What gives? Did I just remember wrongly, or has anyone else faced a similar problem. ND filters ought to be well... as its name implies neutral no?
it kind of reminds me of lousy solar films that people fit on cars and it slowly changes colour over the years as it is exposed to the sun.