First off, thanks very much for taking the time to post such a lengthy message, its much appreciated.
I had bought the ND Filter from a company here in the UK called 7dayshop.com who are usually great with all their photography products, they only cost me £30 each though so Im inclined to believe you may be right in that its a bit crap.
I suppose on the shots that I had issues with I could have stopped up a little but there was still room to stop down with the ND even when I was shooting wide open at F2. I seem to also be getting some reflection when using the ND and i’m trying to work out how to combat that, maybe the glare front he sun, I can’t use my lens hood on the 135L whilst using the ND so maybe I need to try and find a way to approach it slightly differently but still get the results Im looking for. Shallow depth of field is still really important so thats a high priority but the most important thing is for it to look sharp and clean.
Maybe spend some proper money on good NDs? Did I just get a duff one?
Many thanks again
Chris