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Photo Writing is the web version of the Photo Writing mini-magazine produced by Limephoto and Emil von Maltitz since 2010. As of 2015 it is now completely online. Feel free to browse through the articles and please leave comments in the comments section if you would like to engage with us.

Tuesday, March 12, 2019

The Nisi Long Exposure Set

There is something quite depressing about the sound that optical glass makes when it breaks. The initial crack, and following tinkle, that you know is the sound of something expensive going ‘bye-bye’. As it was when my trusty Lee ‘Little Stopper’ shattered, while in the pouch might I add (although the pouch isn’t designed to be dropped - albeit accidentally - in quite that way). I personally think that the 6 stop neutral density filter, aka the ‘Little Stopper’ is actually more useful than the better known 10 stop ND filter, the ‘Big Stopper’ and use it frequently enough that I would have to find a replacement. So, I cast about thinking how to replace the smashed filter.

Some readers will have come across my fairly in depth look at the available filters on the South African market that I wrote about two year’s ago (see this link). At the time I was thoroughly impressed by the newcomer Nisi and their filter offerings. However, since I was happily ensconced in the Lee world of filters I didn’t really have much reason to get rid of what I already had and convert to Nisi glass. That began to change when Nisi brought out a specialised holder for the Laowa 12mm Zero-D lens. I ordered one from LandscapeGear, along with the Landscape Polariser. For the first time I was able to polarize my 12mm, without significant vignetting and still use 100mm grad filters. Then, as my Lee filters scratched (as optical resin is wont to do), I found myself replacing them with Nisi glass filters, and being extremely happy with the results.

The 'Cascades' in the Drakensberg's Mahai Valley - image shot using the Nisi 6 stop ND on a Laowa 12mm Zero D lens

After very little deliberation I opted for the Nisi Long Exposure kit, despite the fact that I already own both versions the  Lee ‘Big Stopper’ (the old one with a terrible colour caste and the new and vastly improved IRND version). The kit comes with three, six and ten stop Neutral Density (ND for short) filters, a dedicated concertina style pouch and a small micro-fibre cloth. Also included are replacement light baffles for the filters. This is a nice touch, although I suspect I may end up losing the baffles before I need them.

The Kit and Using It

The pouch is an interesting addition, and a welcome one at that. Although the kit consists of three filters, the pouch (see the image on the right) has four slots that can fit 100x100mm filters. The fourth slot is a useful space for the Nisi circular polariser. The only problem is if you are wanting to use graduated neutral density (GND for short) filters, in which case you have to have another carrying solution for them (as an aside Nisi make an excellent filter pouch that fits both 150mmx100mm and 100mm square filters which I highly recommend). The pouch is designed to be strapped to the top section of the tripod, so that you have your filters at hand while you are working. I really liked this, but would have also preferred to have another way of carrying the pouch in the form of D-rings for a strap or a belt loop. As it is, the pouch is a little too large to fit into a pocket, so it either stays in the bag, or gets attached to the tripod leg. When attached to the tripod leg though, it works brilliantly. The concertina style doesn’t flap open as much as the Lee Field Pouch, so it means that there is little chance of the filters accidentally sliding out, as has occurred with my Lee Field Pouch on one occasion.

There isn’t all that much to say about working with the filters in the field. They work flawlessly on the Nisi V5 holder, although the size of the holder does mean that it can be a bit tricky to remove a filter if you have a GND in the slot next to it. This is because the V5 completely envelops the filter when in position. This is not a bad thing per se, just that it can be fiddly to work with at times.

Image of Whale Rock on the Wild Coast using the Nisi 10 Stop filter on the Zeiss Milvus 18mm lens

As with all 10 stop ND filters don’t expect to be able to look through the viewfinder and see anything meaningful. It’s more like looking through a welding mask than through a piece of optical flat glass. That said, I was absolutely amazed when both a Nikon D850 and a new Sony A7iii were able to autofocus through the 10 Stop ND! This just goes to show how incredible the autofocus systems have become on the modern breed of digital camera.

Nisi have also done something to the coatings on their filters. While shooting at Luphathana on the Wild coast we were periodically drenched in salt spray. In the past, using other filters I have found this to be an absolute nightmare, as after one or two wipes, the salt content in the spray starts to adhere to the filter and you just end up wiping sticky salt into a smear on the filter. Not so with the Nisi filters (including the GNDs that I had in my kit). Time and again I was able to wipe away the moisture without leaving marks using a micro-fibre cloth. Only when the cloth became truly saturated with salty water did this cleaning no longer work (simple solution…have multiple clothes). 

Most photographers venturing into long exposure photography tend to immediately purchase the 3.0 ten stop ND filter. To my mind this is a mistake. The six stop 1.8 ND is a better ‘first’ extreme ND to use. It’s a lot more forgiving in the way it can be used, is easier to meter with and also easier to shoot with. The complication with the ten stop filters is that they quickly shift the exposure into the minutes as opposed to the second ranges. This means shooting with cabled releases and timing the exposure. It also means being aware of hot pixels and other sensor based ‘noise’ characteristics. Because of this a lot of photographers experimenting with long exposures give up almost immediately. The six stop ND filter is a fantastic in between filter that can still produce the long exposure effect in water without stretching the exposure past 30 seconds. As such is a far easier filter to use to get used to long exposure photography. I also find in my own landscape work (as opposed to architectural and industrial) that extremely long exposures can sometimes create too much of a milky look, and prefer the texture that is still inherent in the slightly shorter exposure.

A three image panoramic of Hole in The Wall using the 6 Stop ND on the Zeiss Milvus 18mm lens

Of course the movement blur in an image is entirely dependent on the amount of actual movement that takes place over the duration of the image. Long exposure photography requires that the photographer pre-visualise to a certain extent the type of look that they are going for in the final image. If a complete misty or milky surface is required in ocean waves, then the ten stop or even greater is required with an extremely long exposure beyond a minute (or longer). Long exposures of a minute or beyond are also particularly important for architectural photography where streaks in the sky are required. They can also be used to remove people from the foreground of images as often people - in the form of pedestrians - would be moving, so therefore not recorded in the final image. If some type of texture in waves and water is still required, then 30 seconds can even be too long. If you are wanting to show movement where the movement is obvious, than a much shorter exposure of about 2-4 seconds is a more likely shutter speed. So essentially, if you are going to explore long exposure photography, one filter is only going to give a taste of the possibilities, whereas as set, such as the Nisi Long Exposure set, will cover most if not all long exposure shooting scenarios.

The Optics

In the past it was essentially expected that neutral density filters would exhibit some kind of colour caste in the final image. Vaunted as it was, the old Lee ‘Big Stopper’ was notorious for having a blue colour caste and significant vignetting on wide angle lenses. This was changed when Lee introduced their IRND glass filters. Gone was the vignette and the colour caste has moved slightly to the warm side of neutral.

The Nisi filters are very similar in the way that they react to light. There is a slight bias towards warming, instead of being spot on neutral. Unfortunately, as with all filters that I have come across since I started using Cokin filters twenty years ago, there is sample variation between batches. So another photographer might have an ever so slightly different result conducting the same tests. Still, the variations are tiny, probably insignificant, and certainly not noticeable in real world photographic situations (barring scientific usage I would suspect).

Below are a series of images shot under studio lighting. The images were shot in RAW and processed through Capture One Pro as a linear conversion. White balance was adjusted for the unfiltered image. The settings were then applied identically to all the other test images to see whether there was a shift based on colour temperature (white balance). The lights were powered up according to the rating of the filters (so three stops for 0.9 ND etc). I did have to boost the ISO three stops for the 3.0 NDs as my lights only had 7 stops of range unfortunately (yes, I am also aware that there might have been colour variance between the power outputs of the lights, but I suspect it would have been virtually undetectable).
Click on the image to open a larger version

Ultimately it doesn’t really affect my image-making at all, but the test showed that all of the filters had a slight magenta caste, apart from the old Lee ‘Big Stopper’ which had a distinctive blue caste. The 0.9 and Lee IRND were the most neutral. However the Nisi 3.0 looks like it has more bite to the image than the Lee IRND. Ultimately the colour caste is moot as it affects the entire image, so can be cancelled easily by simply applying the correct White Balance.

More important Maybe is the actual transmittance. Using a Sekonic L-358 light meter and a constant light source I checked the actual light transmittance of the three Nisi filters. None of them hit the mark exactly, but were within one exposure value. Again, similar to the Lee filters which both showed 0.5EV more blocking of Light than the Nisi. At the long end of the exposure, even a 1.5 EV difference to the stated light transmittance isn’t going to have that much of a difference to the final image, so I would consider all the filters tested (including the Lee’s) of falling within the tolerance levels of my own photography.

Waterfall Bluff shot using the three different ND filters offered in the kit


Not every photographer is interested in long exposure photography admittedly. I tend to use the technique fairly frequently as I quite like the way that time progresses through an image. I find it particularly useful for midday architectural photography as it softens the light falling on buildings when exposures of 2 minutes or more are employed (the edge of shadows are softened with any exposure over 30 seconds in length - the longer the exposure the softer the shadow edge).

In the past, if you wanted to use neutral density filters with a greater density than 3 stops, the choice was fairly limited to using Lee or Cokin/Formatt filters. The former was extremely expensive and the latter fairly terrible in terms of colour caste and sharpness. Nisi isn’t just the middle ground in this. Optically, Nisi glass is on a par with Lee (in the case of the graduated ND filters arguably significantly better), if not better and sharper. In terms of price, they may be more expensive that the Cokin/Formatt options, but represent a better deal when the optical quality is taken into consideration. I am also incredulous as to how easy it is to wipe and clean the Nisi filters while in the field. In the past I used to expect that I would get a certain amount of time with the filter before retiring it for the shoot due sea-spray salt buildup. Using the Nisi filters I don’t even think about this anymore (so long as I have enough lens cloths to keep shooting). Then, when you look at the Long Exposure Kit, the price becomes even more attractive.

Ultimately I find myself strongly recommending the Nisi Long Exposure kit as a filter set. Although it might seem like a cheaper alternative to buy just an individual filter, it is a better image investment to get the whole set. The only downside tot he set is that the concertina pouch doesn’t fit the 100x150mm GNDs, so you really need to get something like the Nisi or Lee Field Pouch instead.

The uMblambonja Stream in the Cathedral PEak section of the Drakensberg - 6 Stop Nisi ND on the Zeiss Milvus 18mm lens

Full disclosure: After returning from a workshop on the Wild Coast where I had been shooting with the Nisi Long Exposure set, I was asked whether I would be an ambassador for Nisi filters in South Africa. I only accept these types of roles when I unreservedly recommend the product (as I did with TriggerTrap). I am happy to promote Nisi since I wholeheartedly believe their product to be superior to the competition. That said, this would not stop me from pointing out flaws within the range. In theory, being an ambassador gives one a certain feedback potential, which translates into an even better product. So although I am now a ‘ambassador’ for Nisi, future write-ups will continue to be as unbiased as possible.

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