Light Pollution Filter Review

This review got its start when Breakthrough Photography sent me one of their Night Sky light pollution filters. While I sometimes receive items I have little interest in, this one intrigued me.

With a clear sky, I took the filter out the night it arrived. Unfortunately, the moon was too bright and I was getting images of a bright sky with faint stars (I needed a moonlight filter). Once the moon cycle improved (from a night photography perspective) and the next clear sky presented itself, I went back out. While the filter needed tested, I'm always looking for an excuse to go out and take in the amazing night sky.

Before I go any farther into this review, I have to admit that I was skeptical, part of my intrigue. Shooting in the dark means there is little light and I struggled to make sense of filtering out some of that light (up to 1 stop of light loss was the figure I was provided). But, light pollution is a real problem for astrophotography for much of the population. So, keeping an open mind, I set up and captured a variety of with- and without-filter comparison images.

With an 82mm sample filter, I opted for the Canon EF 16-35mm f/2.8L III USM Lens mounted to a Canon EOS 5Ds R. The 16-35 L III is one of the best zoom lenses available for astrophotography and, at review time, if any camera is going to detect a sharpness impact caused by the filter, it is the 5Ds R. I opted to use the 18mm focal length because ... I apparently moved the zoom ring slightly from the 16mm mark and didn't notice that in the dark. The Really Right Stuff TVC-34 Carbon Fiber Tripod and BH-55 Ball Head provided the rock-solid support.

With the results loaded, I began with the easy part of this evaluation: sharpness. Fortunately, I could not detect the filter causing any impact to image sharpness. When working with lenses at their widest apertures, only the best provide a tack-sharp image and no one wants even the sharpest results to be compromised. So, the Breakthrough Photography Night Sky light pollution filter checks that box (I wasn't surprised).

Looking at the color impact to images was at least as important to the sharpness testing, but the filter's color impact proved a little more challenging to ascertain (I'll discuss why shortly). I am sharing these results below. I selected two night sky photo scenarios. One has only mild light pollution in it and the other includes moderately strong light pollution from a small town just beyond some hills. For each of these scenarios, I present a set of daylight white balance results and a set of auto white balance results. For each result set, I include a non-filtered image and four with-filter images, including three brightened (+EV) results to use for visual comparison with the base unfiltered image. All images were captured with the same manual camera settings (20 seconds, f/2.8, ISO 6400).

First up, I'll share the daylight white balance comparison with the low light pollution followed by the moderate light pollution examples.

Load Comparison Images

The results produced using the same white balance clearly show the benefit of the filter, producing a much better sky color.

The comparison below shows the histogram difference between the with- and without-filter low light pollution images shared above.

Load Comparison Images

Obvious is that the red channel drops much more significantly than the blue channel.

I nearly always leave my cameras in Auto White Balance mode. Today's cameras usually get the white balance at least close to right and I tweak those images needing further adjustment while post processing. When first looking at the samples presented above, it was more difficult to discern what the filter was doing. Here are the auto white balance results.

Load Comparison Images

In these images, the difference is more challenging to see, but there is still a positive difference being made by the filter.

What does a light pollution filter do?

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Now that you've seen the results, let's circle back and talk about what a light pollution filter does. Most of the world's population lives in areas affected by light pollution and light pollution diminishes our ability to see and photograph the stars, planets, etc. Light pollution filters are designed to cut the artificial light, 570 to 610 nanometers on the visible light spectrum, permitting the stars to stand out. You want to see the Milky Way in the sky, not the city lights.

Build Quality

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While there are other light pollution filters available, the one being tested here is the Breakthrough Photography Night Sky Filter. My first experience with Breakthrough's filters was with their 10-stop neutral density filter. That filter far surpassed the competition, providing impressive color neutrality and lack of vignetting. Since then I've used a variety of Breakthrough's filters and have developed a strong trust in the brand. Breakthrough strives to have the best products on the market and that effort shows in all of their products.

The Night Sky Filter looks great, has a high quality feel and is very light. The X4 traction ring is super easy to grasp for installation and removal which is especially important when photographing in the dark and when wearing gloves, which are more often needed at night.

The filter ring is slim, avoiding vignetting when using the wide angle, wide aperture lenses commonly chosen for astrophotography. Breakthrough uses 16mm on a full frame body as the vignetting-free focal length limit and there are few wider angle lenses available with filter threads.

"Each Night Sky filter is weathersealed in our rugged X4 traction frame and features incredibly durable MRC16 and nanotec coatings for easy and fast cleaning." [Breakthrough] Breakthrough backs this filter with a "25 Year Ironclad Guarantee."

Breakthrough ships their filters in a classy box with a white filter case holding the filter surrounded by foam padding. A red cleaning cloth is included.

Summary

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Photographing the night sky is great fun and these images can be great to have in your collection. If you have any light pollution in the location you are photographing the night sky from, seriously consider adding at least one of these filters to your kit.