Russian photographer Dmitry Evtifeev has been putting Hoya's PRO ND series filters through their paces in a variety of different scenarios. Dmitry looks at why we need ND filters, the packaging and construction of the filters before moving on to test the ND4, ND8, ND16, ND32, ND64, ND100, ND200 and ND500 filters. 

His findings are below, and you can find out more about Dmitry and see the original Russian article on his website. Check out Filterzone for more dedicated filter content, too. 

Contents

Why do we need ND filters?

• Freezing of water flow
• Photographing highways
• Shooting crowded shopping centres
• Special effects
• Astronomical shooting

Packaging and construction of HOYA PRO ND filters

• Density levels and diameters

Testing of HOYA PRO ND filters

• HOYA PRO ND4
• HOYA PRO ND8
• HOYA PRO ND16
• HOYA PRO ND32
• HOYA PRO ND64
• HOYA PRO ND100
• HOYA PRO ND200
• HOYA PRO ND500
• Conclusions

Why we need ND filters

ND filters are needed for reducing light flow. They allow you to shoot with a slower shutter speed that is in certain conditions impossible to do without such filter. For example, ND filters can be used for shooting flowing water when separate splashes became a soft flow. This creates motion effect and image looks more artistic.

Freezing of water flow

Marina Sands skyscraper in Singapore (which is the one with the pool at the top). f/5.6, 5 sec, ISO 100, ND4

View from marina bay, Singapore: f/11, 20 sec, ISO 100, ND8. On the left side there is the fountain which turns into a soft mist thanks to long exposure. 

Singapore River, Singapore. The centre of the city (Clarke Quay area). Due to ND filter and long shutter speed we got traces from the moving lights of the ships (creating the effect of speed. ND filters allow you to achieve such an effect even in daylight). f/4.5, 3.2 sec, ISO 100, ND4

Singapore River, Singapore. Singapore Opera (strange building that looks like a turtle) f/5.6, 10 sec, ISO 100, ND4

St. Petersburg, Russia. Smolenka river f/8, 20 sec, ISO 100, HOYA PRO ND100

St. Petersburg, Russia. Smolenka river f/8, 30 sec, ISO 100, Hoya PRO ND200

Photographing highways

It rarely occurs that moving cars look good in an image. It’s quite another impression when instead of cars there are elongated lines from the beam lights. And every shot will be different because cars always have different speed and trajectory.

Moscow, Russia. Smolenskaya metro area. f/5.6, 20 sec, ISO 100, HOYA PRO ND200 + HOYA PRO ND32

Moscow, Russia. Smolenskaya metro area. f/8, 30 sec, ISO 200, HOYA PRO ND200

Moscow, Russia. Smolenskaya metro area. f/4.5, 30 sec, ISO 200, HOYA PRO ND200

Shooting crowded shopping centres 

ND filters are also useful for shooting crowded shopping malls and squares. In such places people are always moving, so with a long exposure you can get a clear image with nobody in it. For example, I took a picture of the river with ducks.

f/8, 1/125 sec, ISO 100, without filter  

f/8, 30 sec, ISO 100, HOYA PRO ND200

You can see that the water is smoothed and most of the ducks disappeared. The ducks who moved actively are completely gone. The same thing happens at the mall - those who move actively will disappear from the image. This allows you to clear the picture from unwanted objects.

Special effects

Special effects can be created using slow shutter speeds alone. But when your subject is shiny you can’t use long exposure alone without overexposing the image, and ND filters are what you need to balance the exposure. 

f/5.6, 8 sec, ISO 100. ND8 Shooting with a tripod. Zoom effect with long exposure.

Gili Air island, Indonesia. Crohn of the tree illuminated by flashlight. An ND filter gives you enough time to “draw using light" everything that you want.

Gili Meno island, Indonesia. f/4, 30 sec, ISO 200, ND4. Shooting with a tripod, foreground is backlit with a flashlight.

f/4.5, 25 sec, ISO 200, ND4. Shot with a tripod. Trees are backlit with a flashlight.
 

Astronomical shooting

On 20 of March in 2015 a solar eclipse occurred. I used HOYA PRO ND500 and HOYA PRO ND4 filters to capture it.

Unfortunately, I could only use 67mm filters with my Canon 100mm/ f/2.8L IS USM lens. But this focal length is not enough for astrophotography. I have a 1000mm mirror lens of 120mm in diameter and I hope to get ND filters to fit this and capture the next eclipse in 2016.

Packaging and construction of HOYA PRO ND filters 

HOYA PRO ND filters come in a nice strong plastic box. It's sealed with a special tape on two sides.

You can’t unstick the tape without leaving a sticky mark, which is good protection from the "opened-replaced-sold" business. Also, you can’t open the box without unsticking the tape. The HOYA PRO ND series has a metallic coating called ACCU-ND, which is designed not to interfere with white balance and provide more neutral light transmission over the entire area of the glass. The previous generation of ND filters from HOYA and other brands were made by adding metal in the glass material before casting. Thus it was very difficult to achieve balanced neutrality of the filter. Deposition coating technology is considerably easier to manufacture and neutrality of the filter is stable. HOYA PRO ND filters are multicoated from the both sides. Not all ND filters on the market have multi coating, especially not on both sides. Multi coating reduces the possibility of glare, keeping the contrast of the image and reducing almost to zero stray light lost inside the filter.

Density levels and diameters

Testing of HOYA PRO ND filters

The most important question in testing of ND filters is how they change the colour balance of the image. At first glance it seems that the filters are completely gray or black. However, if you look at them from the side, you can see different colour glares.

This is likely due to using different methods of glass dimming. Therefore, there are many opinions about the ability of ND filters to change the colour balance. Moreover, if we take cheap Chinese filters, they obviously distort colours. And the darkest filters are more likely to change the colour balance. While testing I used the Xrite Colorchecker colour scale, which does not change colour under different lightings like paper color scales would.

RAW files were opened in Adobe Camera Raw editor with the grey point third from the right on the above image. White balance: 5000K -9.
When an ND filter happens to have unstable color specifications the white balance will also change. The amount of color shift can be easily checked by the same gray point at the same color sector on the color scale.

HOYA PRO ND 4

The same filter with a glare is on the right. The result with a filter HOYA PRO ND4: 4950K -14. The 50K difference is within the measurement of allowable error and can’t be seen with the naked eye.

HOYA PRO ND 8

The result with HOYA PRO ND8: 5100K-14. The 150K difference can’t be seen with a naked eye. Try to see it in the image below. (I could not).

HOYA PRO ND 16

The result with a filter HOYA PRO ND16: 5100K-14. The 150K difference can’t be seen with a naked eye.

HOYA PRO ND 32

The result with a filter HOYA PRO ND32: 5000K-2. There is no difference.
 

HOYA PRO ND 64

Then I changed the light, so the base white balance moved a little. New white balance: 5300K-3 (without filter). The result with a filter HOYA PRO ND64: 5250K-6.
The 50K difference is within the allowable error and can’t be seen with the naked eye.

HOYA PRO ND 100

The result with a filter HOYA PRO ND100: 5300K-11. There is no difference.

HOYA PRO ND 200

The result with a filter HOYA PRO ND200: 4800K+1. The difference is 500K and this colour shift can be seen in the image below.

Let’s see how it looks on a shoot. Below are some example images:

As you can see such colour shift can be easily fixed by correcting the grey point. The only thing that I noticed is the blue colour became a bit enhanced, while the other colours remained the same.
 

HOYA PRO ND 500

The result with a filter HOYA PRO ND500: 5300K-11. There is no difference.

Conclusions

Considering the fact that almost in all cases the colour balance shift was insignificant (50-150K) and nonlinear, I guess that HOYA PRO ND filters almost do not change the colour balance. The measurement results depend more on artificial light. For example, the colour temperature of the flash may vary within 150K even if it is a good flash meter (like mine).

HOYA PRO ND filters are wonderful and perfectly suited for shooting landscapes. I used to think I could make it only with neutral gradient filters and polarizing filters, but now I must say that ND filters are often indispensable. They can "freeze" the water and clouds blur. They can allow you to shoot bright objects such as the Sun.

For me they are “recommended”, but you don't need the whole range of ND filters. The most demanded are ND8, ND100 and ND500. The rest of the ND filters allow you to adjust necessary density level with more accuracy, but aren't needed so often.

I wish you good shots. And do not forget to stock up on useful filters when going on vacation!

From Dmitry Evtifeev blog

SO 100, w/o f