I knew variable ND filters were immensely useful since you could continuously shoot at the optimum aperture without the need of changing the filters according to the situations. I, however, had never used any variable ND filters that satisfied me in terms of image quality. Variable ND filters I knew could not reduce the light entering into the lens evenly, resulting in poor image quality.
This unevenness is called the X effect as the darker part creates an X-like shape. NiSi claimed that they completely eliminated the X effect with their new ND filter, ND-VARIO Pro Nano. So I decided to give it a try. As usual, I chose the bigger one, 82mm, so that I could use it with most of my glasses. The available filter thread sizes are 67mm, 72mm, 77mm, 82mm and 95mm.
When I opened the box and checked the product, First thing I noticed was the good built quality. After toying it for a while, I also noticed that it rotated very smoothly. As the name suggested, it seemed like a real professional tool.
When do you need to use an ND filter? There are four typical uses.
1. Prime Lens During the Daytime
Firstly, you’d need an ND filter when you use a very fast prime lens during the daytime and shoot at wide open apertures. I like using my Sigma 35mm f/1.4 with the Panasonic GH5 via the Metabones Nikon G to Micro Four Thirds Speed Booster XL 0.64x. This speed booster changes the focal length of the lens 0.64x shorter, that is, 35mm becomes 24mm (48mm in full frame equivalent), while boosting the aperture from f/1.4 to f/0.9. The lowest settable ISO of the GH5 is 100 and the shortest exposure time is 1/8000 sec., which means, if you wanna shoot at f/0.9 during the daytime, you’d need an ND filter.
2. Synced Flashlight During the Daytime
Secondly when you want to use a flashlight during the daytime outdoors particularly when shooting backlit. The variable ND comes in handy as flashlights can’t sync with the camera when the exposure time is too short. The fastest sync speed is typically about 1/250 sec. You usually want to use the shortest available shutter speed (such as 1/250 sec.) to avoid motion blur or hand shakes but you wan to control the depth of field too. A good variable ND filter comes in very handy in such a case as it lets you shoot at desirable shutter speed, aperture and ISO settings.
3. Long Exposure Shots
The third case is where you take a long exposure shot. I often use an ND filter when shooting waterfalls to extend the exposure time to capture the smooth water flow. I used the NiSi ND-VARIO to take the picture of the Kegon Waterfalls in Nikko shown above.
I often combine the NiSi ND VARIO PRO with an ND1000/3.0 (10 stops) filter at sunset or sunrise. As the brightness changes quite rapidly at dawn or dusk, the NiSi ND VARIO PRO comes in handy. I sometimes take experimental shots at dawn or dusk. For example, when I shoot a long exposure shot at dusk, I set the NiSi ND VARIO PRO to the max at the beginning of the exposure and gradually move the knob to set it to the minimum at the end of the exposure, that way, I can capture the light more evenly when taking a long exposure shot during the twilight.
At last but not least, the VARIO ND PRO comes in super handy when shooting videos during the daytime. If you shoot videos often and your camera doesn’t feature internal variable ND filters, you’d need a good variable ND filter. This is because, if the exposure time is too short, say 1/400 sec, any moving element appears unnaturally in videos. Ideally you set the shutter speed to double the frame rate, that is, 1/60 sec when shooting at 30fps to capture motion blur necessary for smooth footage.
I shoot videos quite often these days with my Panasonic GH5. When I shoot videos during the daytime, I always use the NiSi ND VARIO Pro. I shot the video shown below at the same exposure setting (1/60 sec. shutter speed) and rotated the knob of the NiSi VARIO PRO ND filter to adjust the exposure. As you see in the video, the transition is very smooth and it reduces the incoming light evenly without causing the X effect problem.
A good variable ND filter is more preferable than using just one ND filter and unwillingly narrowing down the aperture to get an optimal shutter speed or using multiple ND filters and having to busily change them according to the scene or depth of field you want. You will never regret your purchase if you shoot videos often.
Effects on the Color
OK. The product seems pretty good but how about the color cast? Does it change the color at all? If it does, how does it change the color? Someone asked something like that so I’m now quickly adding this part. Unfortunately it’s cloudy today so I didn’t go down to the lakeshroe to shoot Fuji. I took a tree in the yard instead. I shot these example shots with my Nikon D800E paired with the Nikkor 24-70mm f/2.8E ED VR in Aperture Priority Mode. Note that the brightness of each photograph is slightly different because the camera can only set it in 1/3EV steps.
With no NiSi ND-VARIO
Without ND (1/50sec., f/6.3, ISO100, WB Cloudy)
NiSi ND-VARIO 1.5-stop ND
With NiSi ND Vario MAX (1sec., f/6.3, ISO100, WB Cloudy)
The color changes slightly when using the NiSi Vario ND Pro but the change isn’t necessarily adverse one. In the above examples, some people may prefer the color of the photographs taken using the NiSi Vario. Anyway, it can easily be corrected in the post processing.
I also checked if the NiSi ND-VARIO affects sharpness. Let me show you the 100% crops extracted from the above 3 shots.
The camera slightly moved when I attached the NiSi ND Vario. As you can see, there is no negative effects whatsoever as far as judging from these photographs.
I find this product super useful and can recommend it wholeheartedly to anyone who needs an ND filter. I recommend you to get the ND VARIO with bigger filter thread than that of your go-to lens and use it with step-up rings. When you buy step-up rings, be sure to get ones with knurled sides as you need to change them at times. If they are not knurled you often find it is difficult to remove the rings.