Haida 10 Stop ND filter
This is an excellent quality filter, regardless of the price.
I have used this filter extensively with my landscape work, and it has aided me in getting on the National Geographic website.
I was extremely surprised by the quality of this filter, it seems to be flawless in anyway I can think of. The sharpness stays the same with use – as long as your tripod technique is correct, the colours are actually much richer due to the longer exposure, and there is no colour cast in the slightest.
It doesn't seem to increase flare either.
It is a very slim design and won’t cause any vignetting with most lenses. It has a great easy clean coating – I used this in several days of rain and I just wiped it quickly inbetween shots. Chromatic abberation is no worse with this filter attached.
I’ve heard some people broke theirs when they dropped them, but what do you expect from a thin peice of glass?
Anyway, don’t just take my word for it, here’s some of the pictures I’ve got with it: