NiSi 6 Stop ND Filter ND64 150x150mm Review
I recently reviewed the excellent 3 stop ND filter from Haida in 150x150 size; today I will be reviewing the 6 stop filter for 150x150mm holders manufactured by rival up-and-coming Chinese filter maker NiSi.
Build / Quality
Like Haida, NiSi are using optical glass in their 150x150mm ND filters. I go into greater detail in my Haida 3 stop ND filter review about the merits of glass vs resin in your filters, however the long and short of it is that glass is more scratch resistant while resin is lighter, cheaper and less susceptible to breaking - but is highly susceptible to scratches.
The NiSi employs a foam gasket on the filter to block unwanted light from impacting your long exposures. The shape of this gasket is quite clever, in that by employing a larger and more generous area of coverage, the filter is compatible with more holders and does not require the LightShield to function unlike the SW150 Big Stopper and Little Stopper. I found that the thickness of the foam on the NiSi gasket is fractionally too thin to be a perfectly snug fit with my Haida filter holder, however it is so close that I was not able to see any light leaking even when shining a torch directly into the foam/gap area.
The filter ships in a premium leather pouch sealed by a magnet - and while this looks and feels quality, I can't help but feel it is a waste of money on NiSi's part. Glass filters, especially in 150x150 size are way too fragile to store in such a flimsy pouch when in the field in my opinion; any weight or pressure on the pouch inside your camera bag will snap or crack the filter quite easily. The pouch is not rigid and offers virtually no protection against this sort of weight or pressure induced breakages; it will only protect against scratches. Now to be totally fair generally the competition isn't much better; Haida ship their filters in fabric pouches as do Lee for most of their range, however I imagine these pouches are cheaper to produce which should help keep costs down for the consumer. Lee do supply their Big Stopper and Little Stopper in handy metal tins that offer a good deal more protection than a pouch.
It must be said that while some sample variance in the light-blocking ability of ND filters is to be expected, my copy of the NiSi 6 stop ND filter falls significantly short of the advertised 6 stops. In fact my sample is closer to being a 5 stop ND; I calculated it's light blocking capability to be only 5.2 stops against the claimed 6 stops; a variance of -13% density to spec. I cannot say with any certainty as to whether this shortfall is typical of this model of NiSi filter or if perhaps I have received a bad sample, but it must be said that my copy fails to deliver as advertised in this regard. Below is a comparison of a test image taken without a filter, and then a second image taken with the NiSi filter in place and a manual exposure adjustment of six stops is made. As you can see on mouseover, the image taken with the filter is considerably overexposed in comparison to the image taken without a filter despite exactly six stops of exposure compensation. By dialing in an exposure compensation of -0.8 stops in Camera Raw I am able to achieve a precise matching of exposures between the two frames.
Default image: ISO 64 / f5.6 / 1/4s / no filter / no corrections applied
Mouseover image: ISO 64 / f5.6 / 15s / NiSi 6 stop ND filter / no corrections applied
Fortunately the filter offers a pleasing performance in other regards; delivering a highly colour-neutral output which adds only a hint of a warm cast to the scene when compared against the control image taken without a filter. In fact I believe the NiSi offers an even better performance than my Haida 3 stop in this regard - although the Haida was trivial to correct in post and thus a non-issue, the cast it adds to an image is somewhat more noticeable than the one added by the NiSi here. This is made all-the-more impressive by the fact that the NiSi is a much darker filter than my 3 stop Haida. Thumbs up for colour neutrality. Additionally, not that I expected to see any, but it is worth confirming that there is no visible degradation of image quality as a result of using the filter - the scene is as crisp and sharp as it is without one.
Overall a fairly pleasing performance from the NiSi 6 stop ND filter. Although it loses marks for falling almost one stop short of the claimed light stopping capability, it delivers a highly colour-neutral image, does not sacrifice on resolution or contrast and is well designed using high quality materials.
Please note, NiSi have been providing photographers with filters and kits in recent months in exchange for blogging and reviews of the product. I have no issue with this whatsoever - as long as the photographer writing the review is upfront about that fact. In this instance however, the filter was purchased by me using my own money off the shelf from a local retailer and was not supplied to me by NiSi.