I love the effect of long exposures, and the strong ND filters like the Big Stopper or the B&W ND110 are fantastic, but pricey. There used to be a cheap alternative from Citiwide, but sadly it suffered consistency problems and they stopped making it. I recently decided to add a 6 stop ND32 filter to my lineup, for the evenings when the ND110 was just a bit dark. I ordered a 77mm ND32 from a UK seller on ebay and the initial results are promising. It is actually darker than the B&W (by about 2 or three stops I think) and it was only £12. Seems to be glass and decent quality (for a £12 filter). It has a bit of a blue tinge on long exposures and vignetting is evident at wide angle (I think this is due to the increased density as a result of the angle of light entry, it is not from the mount. You also see it with the dark welding filters which are much larger than the front of the lens). Anyway, more results when I have had a chance for a thorough play with it.