(No, We’re Not Crazy) Why You Should Use a Circular Polarizer at Night

I had another “What if?” moment, dear readers.

It was this: What if I use a circular polarizer at night?

My mind boggled. It balked. It basically said, “There are tons of reasons you should not even consider doing that.”

Such as:

  • You’ll lose up to 1.5 stops of light! My precious light …

  • It’s going to be hard to see the effect through the lens.

  • A polarizer is another thing to carry and/or take care of. (Have you seen my backpack? I call it the “kitchen sink.”)

  • Your sensor will capture fewer stars—perhaps?

  • You may be disappointed.

So What?

Despite all those naysaying, braying voices in my head, I set about scraping out some moments during our Rocky Mountain National Park workshop to run some experiments.

Why? Well, I know polarizers have these positive traits:

  • minimized reflections, making water easier to see through

  • more vibrant colors and deeper saturation

  • reduced highlights, which puts more of the exposure inside the dynamic range of my camera

  • eliminating or reducing off-axis light

That last one was really exciting to me, as we would have lots of moon at Rocky Mountain, as well as at our workshop immediately afterward at Chaco Culture National Historical Park.

Maybe, just maybe, I could make a polarizer do something useful—or even something amazing.

Note: Since my polarizer was a screw-in 95mm, I did not go through the hassle of removing it during tests. I simply set it to minimum effect for the “before” images and maximum effect for the “after” images.

Testing My Hypothesis on Star Trails

So I set out to test my hunch that it would work. After all, it’s just science, right?

On our final day of the workshop, we embarked on an add-on adventure with five attendees, during which we hiked with our gear almost 2 miles (one way) with 650 feet of elevation gain at over 8,000 feet of altitude. It was challenging, but we did it.

Our first shoot location, Emerald Lake, had a moon shadow slipping around to the right. The moon was at my left shoulder—ideal conditions to make a polarizer work.

Tip: Polarizers work best when used perpendicular to the light source (90 degrees). So keep the moon (or sun, if you are so inclined), on your right or left shoulder.

I set the polarizer to minimum effect:

Nikon D850, Zeiss 15mm Distagon f/2.8. 30 sec, f/2.8, ISO 6400.

Exactly what I’d expected. Not a lot of stars. So I turned off my camera, peeped through the viewfinder, turned the polarizer and found the area of deepest effect:

Nikon D850, Zeiss 15mm Distagon f/2.8. 30 seconds, f/2.8, ISO 6400.

I was so excited (and it was so cold) that I settled into a sequence of eight 7.5-minute exposures, totaling one hour:

Nikon D850, Zeiss 15mm Distagon f/2.8. Eight frames at 7.5 minutes, f/2.8, ISO 6400.

Booyah. Many stars, despite shooting with broad moonlight. It worked!

As we started hiking back down, we stopped at Dream Lake. I wandered to the south end of the lake with a student and set up another test, this time with stiller water. (There had been crazy wind up at Emerald Lake.) I ran two high ISO tests at 15 seconds, f/2.8, ISO 6400:

I loved what was happening so much that I wanted to grab two 15-minute exposures to compare:

(I wish I’d done the “without” photo first, because the moon came out more during that exposure.)

So, then I had another “What if?” moment during editing. What if I used the water from the zero-polarizer shot and masked it in to the yes-polarizer shot?

Nikon D850, Zeiss 15mm Distagon f/2.8. 15 minutes, f/2.8, ISO 100. Maximum polarization (in the sky portion).

Again, a wonderful solution for pulling out more stars and deeper, darker skies. Plus, if you shoot both, you can choose the best of each and blend them together. That’s powerful stuff.

And then the Rocky Mountain workshop was over. … But I had another workshop (with Lance) in two days, so Chris and I hustled down to Chaco Culture. And during the second-to-last night, I had a couple of moments here and there to test again.

Facing north, I wanted to test how many stars I could capture at f/13 for a star trail rip.

Test shot No. 1. Nikon D750, Zeiss 15mm Distagon f/2.8. 25 seconds, f/11, ISO 3200. Maximum polarization.

Test Shot No. 2, with a different polarizer orientation: Nikon D750, Zeiss 15mm Distagon f/2.8. 25 seconds, f/11, ISO 3200. Three-quarter polarization.

I felt it had better skies. I wanted a touch darker, so I dropped to f/13 and I committed to a one-hour shot with Long Exposure Noise Reduction turned on.

I admit, I had to do some post work to pull out the stars on the skies, but they’re there!

Nikon D750, Zeiss 15mm Distagon f/2.8. 1 hour, f/13, ISO 50. Three-quarter polarization.

I think next time I’ll shoot such a photo at f/8 to see a touch more stars. But it’s not the normal, cluttered sky we get without polarization and a much wider aperture. And the sky in the background is darker—much darker—which is something we don’t generally see when shooting in moonlight.

But what about the Milky Way?

Well, what about the Milky Way? It’s a silly question, right? You can’t shoot the Milky Way on a moonlit night.

Or … ?

This last test, if successful, would be the coup de grace, on my circular polarizer experiments. Can I extract a Milky Way from moonlit skies? It was an idea raised by Jason, a Rocky Mountain attendee who was on that hike with us the week before. And now I could try it out.

Now in New Mexico, we were shooting at Pueblo Bonito, the park’s showpiece ancient structure, which features over 600 rooms plus multiple kivas of fascinatingly intricate architecture.

There was a 25-minute window of darkness between the end of twilight and moonrise. We hustled to nail the Milky Way during that window, but I suspected I had an advantage with a circular polarizer and hoped I could make it appear even after moonrise.

As soon as the moon rose, people started repositioning to re-frame to make the Milky Way less important. They couldn’t see it. But … maybe I could?

First shot, with minimum polarization:

Nikon D750, Zeiss 15mm Distagon f/2.8. 25 seconds, f/2.8, ISO 6400. Minimum polarization.

And then...

Nikon D750, Zeiss 15mm Distagon f/2.8. 25 seconds, f/2.8, ISO 6400. Maximum polarization.

Double booya. Ignoring the fact that someone did light painting in the foreground for this shot, check out that Milky Way! This is not a composite. It’s one frame, with some Lightroom adjustments.

You may notice that the area of sky around the Milky Way is darkest. That’s not from a local adjustment in post, but rather that’s where the circular polarizer’s effect happens. I strategically placed the effect right along the axis of the Milky Way. The polarization occurs only in that area (rather than the whole sky) because I am using a superwide lens and the effect covers a limited angle.

Anyway, back to the exciting part. I was able to shoot a clear Milky Way sky with a full moon lighting the landscape. My whoops of pleasure resonated from the canyon walls. I let out massive yawps of glee.

Folks, a revolution has arrived. You can put one more big gun in your bag to make your night skies sing. You can use a polarizer to photograph the Milky Way in moonlight.

When Does a Circular Polarizer Not work?

One caveat: When using ultrawide-angle lenses (like my Zeiss 15mm Distagon), you will discover that the area affected by polarization can be narrower than you want.

Check this out—I adjusted the polarizer all around to find a sweet spot, but didn’t find one: (

I also experienced some flare when the moon was at the edge of my ultrawide lens in the above.

So to avoid these two things that I found disadvantageous, I switched lenses to my 35mm, went vertical with a lens hood, and made a pano stitch (without a polarizer), and am very happy.

Note: Polarizing with pano stitches is rarely successful.

Nikon D850, Sigma 35mm f/1.4 Art. Ten frames at 10 seconds, f/5, ISO 6400. No polarizing filter.

So watch your images to be sure the effect is one you want to commit to, but give it a shot.

Wrapping Up

A circular polarizer is definitely worth putting in your toolkit for night photography. ’Nuff said.

And I can’t wait to see what you do with this! Please test for yourself and post your results in the Comments section here or on our Facebook page. We’d love to see what amazing things you make.


For you gear geeks: I used the Benro Master Slim Circular Polarizing screw-in filter on my Zeiss 15mm Distagon.

In case your superwide lens doesn’t accept a screw-in, know that many manufacturers, Benro Filters included, now make 100mm and 150mm square filter holders that allow for a circular polarizer to be mounted, as well as neutral density and graduated neutral density filters. It’s an amazing photography world we live in these days.

Matt Hill is a partner and workshop leader with National Parks at Night. See more about his photography, art, workshops and writing at Follow Matt on Twitter Instagram Facebook.


The Night Photography Game-Changer: Day for Night Filters Now Available

At first glance, the National Parks at Night mission might appear to be solely about venturing into parks in the dark to teach night photography. But our broader mission is much … well, broader. It’s about pushing the envelope for the entire world of night photography.

To that end, we’ve been quietly working hard for the past 14 months to develop our first tangible product—a set of tools that will at once help established night photographers expand their creative potential and give new night photographers an easier way into the niche.

And finally, we are very proud and excited to announce the National Parks at Night “Day For Night Filters.”

prodcut 5.jpg

This is a toolkit of seven classes of filters—available individually, in sets or in one comprehensive package—designed to allow certain types of night photography to be executed even when conditions aren’t right for traditional approaches to shooting in the dark.

The idea behind the filters is born from the old-time filming technique of “day for night”—essentially, using daytime light conditions to produce a nighttime look. But while the film crews of yesteryear generally accomplished this effect simply by underexposing, this toolkit goes a step further.

How The Filters Work

All our filters feature a neutral density (ND) base layer, which is then etched to produce different common astro-landscape looks when photographing a daylight scene. The etched portions allow daylight in while the ND portions keep other areas dark. The combination allows for a wide range of effects, from star points to star trails to the Milky Way and even auroras! Plus much, much more.

The ND portions, however, are not completely neutral—they have a cool-toned coating (mired-blue, for the tech-minded reader) that produces a truer “nighttime” look. Conversely, the etched portions of the filters have a mix of warming tones. This DualTemp (patent pending) combination of these two color-correcting filter technologies produces images that look exactly as if they were photographed at night.

The Toolkit

Our initial rollout is a selection of filters crafted to reproduce the most popular night photography scenarios, as detailed below.

(Unless otherwise noted, all filters are available in rectangular format in sizes 85mm, 100mm and 165mm.)

Star Points Filter

The most basic of our Day For Night Filters is the “Star Point,” which allows you to photograph “under a night sky” no matter what time of day you’re shooting. The neutral density overlay is pocked with tiny pits, each a different size with subtle variations in color temperature, all of which combine to create a highly realistic starry sky effect when shot with daylight color temperatures.

The Star Points kit includes three filters with different densities of stars, for maximum creative leeway.

Star Trails Filter

Sometimes stationary stars aren’t enough. Enter our “Star Trails” filter, which allows you to create the illusion of bending time, even with considerably short exposures.

These filters come in different star densities (low-density for fewer star trails, high-density for more), and also come in different trail lengths (4mm, 16mm and 32mm) to mimic various long-exposure times. The entire set will allow for maximum creativity, giving the option to swap in different effects for different scenes.

Star Circles Filter

One of the coolest tricks to round out the night photographer’s repertoire is the ability to produce star circles by pointing north on a clear night and opening the shutter for a good hour or more. But now you can create the same effect pointing in any direction (opening up many more possible compositions), and in much less time!

Our “Star Circles” filters come in two varieties:

Rectangular, which offers a fixed set of star circles that can be positioned to suit the composition by moving the filter up or down in the holder.

Circular, which features a rotating ring that makes the star trails shorter or longer.

Milky Way Filter

Perhaps the most popular night photography achievement of the past decade is the ability to capture the dense cluster of stars of the Milky Way. But even though modern camera technology has put our galaxy in reach of shutterbugs throughout the solar system, photographing it still comes with challenges—namely, having to wait for the right time of year to view it, the right time of night for it to appear over the horizon, and its propensity to hardly ever be hovering in a compositionally pleasing place in the scene.

All those issues are solved by using our “Milky Way” filter. It comes in a standard rectangular format, which enables you to place the galactic core anywhere you want in the sky of your composition, and you can then adjust the angle of the core by rotating your filter holder.

Moon Phases Filter Kit

Normally, if you have a solid idea of how you want the moon to look in a scene, you need to do a lot of planning to make it happen. Earth’s only satellite floats all over the night sky, and its particular phases appear only once per month.

All these challenges dissipate once you begin using our “Moon” filters. A set of 10 filters allows you to add the moon to any scene, in any way you want. The entire “Moon Phases” kit features the moon in three different sizes (grande, venti and trenta) and four different phases (full, quarter, crescent and new).

Moon filters can be used alone for a clean-sky effect, or stacked with Star Point filters for a combined, starry sky effect.

Aurora Filter

We almost didn’t manufacture this filter because of the technical complications first in manipulating the necessary technology, and then in actually constructing the glass. But to be honest, it’s the filter we’re most excited about: the “Aurora.”

Until now, photographing auroras has been the playground only of those willing to travel to far-flung polar regions, such as the popular photography destinations of Iceland, Norway and Red Dog Mine, Alaska. But if you want to shoot the northern lights from your own back yard, then this filter is all you need.

Our Aurora filters come in two varieties:

Rectangular, which offers a fixed aurora that can be positioned to suit the composition by moving the filter up or down in the holder.

Circular, which features a rotating ring that changes the shape of the aurora!

(If you live in the Southern Hemisphere, please be sure to order the “Southern Lights” filter for the most accurate results.)

BONUS! — The Keimig Firework Filter

For a limited time only, free with any purchase of three or more filters is an out-of-the box idea from National Parks at Night partner and instructor Lance Keimig, whose motto is, “There’s no night landscape that doesn’t look better with fireworks!”

The “Keimig Firework Filter” is rectangular, making it positionable so that you can place the firework where it serves the composition best. Now any day (or night) can be the 4th of July or New Year’s.

(Coming this December, be sure to look out for our “Keimig Kristmas Lights” filter set, which will accomplish similar results. Decorate the rim of the Grand Canyon!)

Filters That Solve Problems

We’re confident that our Day For Night filters will solve many of the entry barriers to nocturnal photography, and will also help ease the burdens of experienced night photographers. Quite simply, night photography is hard, and these filters make it easier.

  • No more need to wait for Milky Way season.
  • No more need to travel to aurora “destinations.”
  • No more in-the-dark focusing hassles.
  • No more looking for something to do during crazy-long exposures.
  • Get to sleep at a reasonable hour.

How to Purchase

All of our Day for Night filters are being carried exclusively by B&H Photo in New York City, as well as the camera department of the General Store in Bodie, California, and are available for purchase immediately. Please click the button below to order.

Get Creative!

The only thing that excites us more than developing and releasing these filters is that now we get to see what you do with them. We encourage you to get out into the field, use these great new night photography tools, and share your images in the comments section.

Seize the night! (Or day!)

Chris Nicholson is a partner and workshop leader with National Parks at Night, and author of Photographing National Parks (Sidelight Books, 2015). Learn more about national parks as photography destinations, subscribe to Chris' free e-newsletter, and more at


Night in Day: How are you Preparing for and Shooting the Eclipse?

Note: This article is also featured in our brand new free e-book Here Comes the Sun: 2017 Solar Eclipse Guide. The e-book also includes the articles “Parks in the Dark,” a travel guide to all the National Park Service units that the total eclipse will pass over, and “The Right Stuff,” a detailed buyer’s guide for all things related to eclipse photography. Download your copy today!

If you haven’t heard the buzz yet, the continental United States will be experiencing a solar eclipse on August 21. If the weather is good, we will all be able to see … most of it. But lots of lucky folks will be driving to a spot along the path of totality to experience something very rare and surreal: the total eclipse, when day turns into night. For approximately 1 to 2 minutes you’ll be able to see the stars during the day and the wild corona light dance from behind the moon.

The last total solar eclipse to touch the lower 48 was on February 26, 1979. The last time we experienced a total solar eclipse crossing our entire nation from the Pacific to the Atlantic was on June 8, 1918. That was a long time ago; it’s pretty rare.

The good news is that, at least this time around, it won’t be rare for long. The next total solar eclipse in the U.S. after 2017 will be in 2024, when the path of totality will cross from Mexico into Texas and will leave via northern New York and New England on its way to New Brunswick and Newfoundland. So any specialized gear you get now, you can put to good use in seven years!

The last trans-U.S. total solar eclipse happened … well, awhile ago.

Gear you Need to See and Capture

As you have probably guessed in life, it is not a good idea to stare at the sun. The most important thing you can purchase to prepare for the eclipse is a pair of solar glasses for your eyes and solar filters for your camera lenses. Technology continues to get better in this field and the newest international standard rating is ISO 12312-2. If you do not see this certification on the product, you shouldn’t purchase it. Solar filters absorb the ultraviolet, visible and infrared energy of the sun, making our star safe to view and photograph.

Protect your eyes with solar glasses. (Helmet is optional.)

B&H Photo, home of my day job, has been a great resource for embracing the best products and knowledge. To that end, I have been recently practicing shooting the sun and want to share this knowledge with you.

As far as glasses go, any simple paper pair will do, as long as it has the aforementioned ISO rating. A cool thing that B&H is doing is packaging free solar glasses with most of their solar filters! So you can kill two birds with one stone, all while not killing your eyes or camera sensor.

Let’s focus on the filters from a photographic point of view. There are three types of solar filters you can choose from:

  • screw-in filter
  • glass drop-in filter for a filter holder system
  • inexpensive and universal paper or adjustable aluminum alloy filters that are easy to take on/off

The screw-in filter is the one I would least recommend. Even though it seems to be the most popular, think of this: The common strategy for shooting the eclipse is to have a filter over your lens so that you can capture a properly exposed and non-flaring sun. Once we enter the small window of totality, when the moon will eclipse the sun, it will be safe to take the filter off and adjust your exposure accordingly for that beautiful shot of dark sky and the white ring around the moon. You must wait until after the “diamond ring effect”—when the sun flares one last time from behind the moon—before taking off the filter. You don’t want to waste precious time (5 to 10 seconds) unscrewing a screw-in filter when you could instead take 1 to 2 seconds to remove a drop-in filter or universal filter cap. The average time of totality will be from 1 to 2 minutes and you want to photograph it but also experience it. Don’t waste precious time fumbling around with your gear!

If you want to look into the available filters and other eclipse equipment, an easy way is to search all the gear and articles that B&H has been working on for the last year. Type “Solar Eclipse” into the search engine at and you’ll be taken to this very resourceful page:

Start Practicing Now

The first time you shoot the sun shouldn’t be on August 21. Get some solar filters and start practicing shooting the sun now! I’ve been doing this over the summer, which has given me a chance to test exposures and specific gear before the big day.

I recently purchased the Solar Eclipse Filter by Lee for my Wine Country Filter Holder system, as well as the Daystar universal solar lens filter. My MrStarGuy Adjustable Objective filter is on back order, but should be shipping soon.

Lee is one of the top-end filter companies. Their filter mentioned above is equivalent to a 20-stop neutral density, but also is ISO certified and should be used only for solar work—not for long-exposure landscape photography.

Wine Country Filter Holder system and 100-400mm lens.

The Lee filter is made of glass, and I find the image quality is excellent. The suggested settings from Lee with this filter are 1/800, f/8, ISO 800. Think crazy eights! This was pretty spot-on while the sun was high in the sky around 2 p.m.

With Auto white balance, I found the Lee filter produced a clean white sun. I experimented with the white balance and preferred cranking it to 10,000 K for a nice yellow/orange sun that is more visually familiar. You can see the two compared below:

I also tested the Daystar slip-on filter and found that to be of very good quality as well. It was a bit deeper orange/yellow than the Lee with the white balance set to 10,000 K. I also found the Daystar to be 1 1/2 stops faster than the Lee, as my final exposure setting was 1/500, f/5.6, ISO 800.

Sun shot with Daystar filter at 10,000 K white balance. 1/500, f/5.6, ISO 800.

Sun shot with Daystar filter at 10,000 K white balance. 1/500, f/5.6, ISO 800.

Lens(es) and Game Plan

There are multiple ways to capture and create some unique images of the eclipse. Search Google Images to see what resonates with you.

I definitely recommend using a telephoto lens and getting a somewhat tight shot of the different phases of the eclipse. The careful thing to consider is not getting in too tight. When the total eclipse starts you’ll see the breathtaking corona light start to spill out from behind the moon. This can spread pretty far and create some beautiful patterns. If you are in too tight, you’ll frame it out.

When testing, I was using a 100-400mm lens on an APS-C crop sensor, and the far end of that focal range seemed like the sweet spot for a good telephoto capture. That’s 600mm to 800mm with a full-frame sensor, which you can achieve with really big glass or with a 1.4X or 2X teleconverter. But if you have a crop-sensor camera, that would be the one I’d lean on for this project.

The trick to the telephoto shots will be tracking the sun as it quickly moves through your frame. Depending on how tightly composed your shot is, this setup could require constant attention and adjustments. Having a sturdy tripod is a must, especially if you add a tracking device to a long lens and camera. Make sure your tripod head and legs are rated to hold the combined weight over a long period of time.

Many people will be using digiscoping (attaching a camera to their telescope) to get even closer images of the sun and eclipse. We really haven’t experimented with digiscoping at NPAN, but our good friend Todd Vorenkamp at B&H Explora discuses those considerations in his very informative article, “How to Photograph a Solar Eclipse.”

I’d also bring another, separate camera setup for capturing a wider view that includes the landscape. The telephoto phases of the eclipse are cool to capture, but they are generally featured against a dark black sky. If you use a medium telephoto or wide-angle, you can include some subject matter that gives your composition depth and scale. You’ll still need to have that solar filter on to capture more phases of the sun, but you’ll also want to get a properly exposed foreground—ideally once the uneclipsed sun is well out of the frame—to layer together in Photoshop.

Two tips to consider when using that technique:

  1. Underexpose the foreground shot so all the solar disks will stand out against that hopefully deep blue sky.
  2. Once the eclipse starts to happen, keep an eye on your settings and make adjustments to open up your exposure as the sun gets thinner and fainter.

Be Flexible and Keep an Eye on the Weather

This is going to be the most viewed and recorded solar eclipse ever. You’ll be able to watch it in and around populous cities such as Kansas City, St. Louis, Nashville and Charleston, as well as in national parks such as Great Smoky Mountains and Grand Teton, and in many rural national and state forests.

Do you want to experience this event in a city or town with tons of people and lots of rooftops and amenities, or do you want to go someplace more remote and get a darker sky?

Staying flexible with weather is key. There are plenty of apps (we like Weather Underground) that can share predicted cloud cover. It’s a good idea to have a Plan B and C that are within a 1- to 3-hour drive from your Plan A. You obviously want to avoid overcast and thick cloud cover, but sometimes stray clouds and wisps are unavoidable. Do your best to adapt or adjust—we are wishing you the clearest of skies, of course!

Most hotels are sold out within the path of totality, but campgrounds and private property are “renting” space to eclipse chasers. I will be leading a sold-out workshop with NPAN at a private ranch in the Centennial Valley in Montana, but we will dip down into Idaho to get into the path of totality. We will also be participating with Atlas Obscura and B&H Photo on a Total Eclipse festival in eastern Oregon that just sold out. (There is a wait list that they might open up—click here for more info.)

To find more events in areas that you will be close to, check out these listings:

Don’t forget to enjoy and EXPERIENCE it!

Sure, most of the United States will be watching the eclipse on TV, and that is … two-dimensional. But to actually experience the eclipse is something very special. Animals and humans both react to this astronomical phenomenon in extraordinary ways, and nothing can really prepare you for when the darkness takes over the land and sky. There is a reason people become eclipse chasers and travel the world to keep searching out this experience. Each eclipse and location is unique and different. We look forward to sharing photos of ours with you and vice versa.

A couple of other fun things to prep you for the eclipse:

  • Read Tyler Nordgren’s book Sun, Moon, Earth—A History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets. We are also a big fan of Tyler’s other book, Stars Above, Earth Below—A Guide to Astronomy in National Parks. He makes the science of astronomy very engaging, easy to understand and to get excited about.
  • Send an eclipse to someone you love! The United States Postal Service has released a unique Total Eclipse of the Sun forever stamp. The stamps show the total eclipse, but when you touch them with your finger the eclipse reveals the moon. They used thermochromic ink that reacts to the heat of your finger! So stock up on these stamps and send a letter or post card from wherever you are experiencing the eclipse!

Download our Eclipse E-book

Finally, if you want to learn some more about how and where to photograph the eclipse, download our free Here Comes the Sun: 2017 Solar Eclipse Guide e-book today! It includes this article, along with a travel feature about all the units of the National Park Service in the path of totality, as well as recommendations about photography gear and services, and eclipse information and swag.

Carpe eclipse!

Gabriel Biderman is a partner and workshop leader with National Parks at Night. He is a Brooklyn-based fine art and travel photographer, and author of Night Photography: From Snapshots to Great Shots (Peachpit, 2014). During the daytime hours you'll often find Gabe at one of many photo events around the world working for B&H Photo’s road marketing team. See his portfolio and workshop lineup at


Level Up With Light Painting: Correcting the Color of Your Flashlight (Part II)

Note: This is the conclusion of a previous post, “Level Up With Light Painting: Correcting the Color of Your Flashlight (Part I).”

In my last post on flashlight color I demonstrated how LED flashlights produce a cooler light than I prefer. I went on to show you how to analyze and correct the color using simple gels from the Roscolux Swatchbook.

In that post, the filtration I worked out for my favorite flashlights—the Coast 300-lumen Coast HP7R and 185-lumen Coast HP5R—was a Roscolux 1/2 CTO combined with a 1/8 minus green. This combination works well when my Nikon’s white balance is set to Direct Sun (Daylight on a Canon). Night photography, however, often requires a significant deviation from our common white balance settings.

Finding the Fix

Direct Sun white balance has an approximate Kelvin temperature of 5500. Although, as I mentioned in my last post, Lightroom may display your Kelvin temperature higher or lower depending on Adobe’s interpretation of your camera. Adobe interprets my Nikon’s D4s’s white balance as 4900 K. For the remainder of this post I’ll refer to the Kelvin setting on the camera rather than Adobe’s interpretation.

When using the Direct Sun white balance setting, subjects photographed under average midday sunlight will be rendered properly with regard to color. If, however, your white balance is set to Direct Sun and you photograph a subject under a different light source, the subject will take on the color cast of that light source. For example, for the photo in Figure 1, I kept my camera set to Direct Sun white balance while photographing under the heavy orange cast of the sign lights. Figure 2 shows the color-corrected version at 2000 K.

Figure 1. 5500 K (Direct Sun) white balance

Figure 2. 2000 K white balance

Lowering that white balance had the effect of adding in a blue cast, counteracting the orange/yellow cast it had before. Now imagine if I had used my somewhat blue LED flashlight to paint the people in the foreground. After color correction, the subjects illuminated by the flashlight would be even more blue due to the lower Kelvin temperature.

So while the filter combination I used for my flashlight worked well with Direct Sun white balance, that same filter combinations would turn the flashlight light to blue when using white balance settings typical of night photography.

Finding the Filters

How to resolve this issue? Once again I turned to my X-Rite ColorChecker chart for my visual tests. I began by setting my camera’s white balance to Tungsten, which is roughly 3200 K. This is a setting I often use for night photography. Next I light-painted the chart with my standard filtration of 1/2 CTO combined with a 1/8 minus green. This produced the color in Figure 3.

Figure 3. 3200 K white balance, Coast HP7R filtered with Rosco 1/2 CTO and 1/8 minus green filter gels

Figure 3. 3200 K white balance, Coast HP7R filtered with Rosco 1/2 CTO and 1/8 minus green filter gels

The chart is noticeably cool due to the lowered white balance setting of 3200 K. So I experimented with a variety of gels, looking for the right mix to produce a more accurate color balance. After experimenting, I settled on a Roscolux Dark Bastard Amber, which when added to my 1/2 CTO and 1/8 minus green, produced the effect we see in Figure 4.

Figure 4. 3200 K white balance, Coast HP7R filtered with Rosco 1/2 CTO and 1/8 minus green  plus  Dark Bastard Amber filter gels.

Figure 4. 3200 K white balance, Coast HP7R filtered with Rosco 1/2 CTO and 1/8 minus green plus Dark Bastard Amber filter gels.

You can see that new combination of filters has produced a color cast that is neutral to slightly warm when shooting with Tungsten white balance.

Putting This Into Practice

For the last step, I took a new clear plastic filter from a Coast LF100 filter kit and again traced and cut out a 1/2 CTO, a 1/8 minus green and a Dark Bastard Amber, and taped them all to the filter. Now I can easily interchange the two plastic filters (one with my original gel combo and the second with the original combo plus Dark Bastard Amber) when I change my white balance from Direct Sun to a Tungsten.

Figures 5 through 8 show a real-world example of how this affects the color of a scene. In Figure 5, my camera’s Direct Sun white balance produces an overly orange image due to the sodium vapor lights (common in most city lighting) illuminating the building.

Figure 5. Direct Sun white balance

Figure 5. Direct Sun white balance

Figure 6 shows the same scene after I changed my camera’s white balance to Tungsten (3200K). Notice the nearly neutral color of the metal and white door.

Figure 6. Tungsten white balance

Figure 6. Tungsten white balance

For Figure 7 I kept the white balance set to Tungsten and illuminated the door with my unfiltered flashlight. The door becomes very blue due to the cooler white balance setting.

Figure 7. Tungsten white balance with unfiltered flashlight illumination

Figure 7. Tungsten white balance with unfiltered flashlight illumination

Figure 8 shows the same scene with my camera still on the Tungsten white balance setting, but light-painted with the flashlight gelled with the 1/2 CTO, 1/8 minus green and Dark Bastard Amber combination.

Figure 8. Tungsten white balance with filtered flashlight illumination

Figure 8. Tungsten white balance with filtered flashlight illumination

Of course, Tungsten white balance is not the only setting I use for night photography. My night settings range from 3200 K to 5500 K, with 3800 K being the setting I use most often. So, you may ask, why did I run my test at 3200 K if use 3800 K more often? In a word, warmth. I like my flashlight illumination to be somewhat on the warm side. A gel that produces a neutral cast at 3200 K will produce a warmer cast at 3800 K. Just how I like it!

Remember, no LED flashlight will produce perfect color. But, with a little testing and experimentation, you can create your perfect color for your light-painting illumination!

Learn more techniques from Tim Cooper’s book The Magic of Light Painting, available from Peachpit.


Level Up With Light Painting: Correcting the Color of Your Flashlight (Part I)

For the photographer who enjoys light painting, the flashlight (or “torch,” if you are a Brit) is your most basic tool. However, all flashlights are not created equal. They come in a wide variety of intensities, beam patterns and color variations. In this post I’ll deal with that last variable, and show you how to control the color of this essential tool.

Defining the Color Problem

While incandescent flashlights have been the norm for a very long time, today the most commonly found flashlights use LED (light emitting diode) technology. The LED is superior in many ways. LED flashlights are more resistant to shock, are easily dimmable, and last much longer than a typical incandescent bulb.

The downside is that LED flashlights rarely have the nice warm color that was so common in our old household Everyready or Maglite. Most LEDs produce a cooler blue or even greenish color. For photographers working in black and white, this is a non-issue. But color photographers might want to determine their flashlight’s color cast so they can add the proper filtration to obtain a desired color temperature.

Measuring the Discrepancy

Like most folks, I don’t own any special color meter equipment, so I set up a simple test using the tools that I had on hand: My Nikon D4s and Gitzo Series 2 Traveler carbon fiber tripod, an X-Rite ColorChecker color-test chart, Adobe Lightroom, and my Coast HP7R flashlight. (I should note that the HP7R is an amazing light, one of the workhorses of my kit—the fact that I’m using it for this test does not denote a shortcoming with this model in particular, but rather with the LED technology as a whole.)

I set up the color test chart in a dark room. With my camera on the tripod and white balance set to Direct Sun (Daylight on a Canon), I illuminate the test chart with my flashlight and take a picture. Notice the cool color cast of the resulting image in Figure 1? The daylight white balance of the camera shows us the natural bluish cast of the flashlight.

Figure 1. Bluish color cast of the Coast HP7R flashlight, typical of many LED flashlights.

Figure 1. Bluish color cast of the Coast HP7R flashlight, typical of many LED flashlights.

To determine the exact color cast, I import the image into Lightroom and open it in the Develop module. The area at the top of the Basic panel displays the image’s white balance setting.

When shooting your camera with a white balance setting of Daylight, you would expect this reading to be 5500 on the blue-yellow axis and 0 on the green-magenta axis. The numbers we see here, however, are Adobe’s interpretation of my camera’s file. Adobe sees my camera as 4900 on the blue-yellow axis and +1 on the green-magenta axis. The fact that these numbers (Figure 2) don’t match the traditional daylight Kelvin temperature of 5500 is not a big deal; remember, this is just Adobe’s interpretation.

Figure 2. Adobe’s interpretation of my camera’s white balance when shooting with the unfiltered HP7R.

Figure 2. Adobe’s interpretation of my camera’s white balance when shooting with the unfiltered HP7R.

Next I grab the White Balance Selector tool (circled in red in Figure 3) and click on one of the light gray patches of the color checker chart.

Figure 3. The White Balance Selector tool.

Figure 3. The White Balance Selector tool.

The White Balance Selector is a great tool for color-correcting when you have a known neutral color in a scene, such as the gray areas of this chart (which I carry with me for times when I need to get precise color correction under artificial lights). When you click on an area of the image with this tool, Lightroom tries to balance that area to a neutral color, resulting in no color cast. Figure 4 shows the image after I click on the light gray patch. Notice how the cool cast is removed from the image, resulting in neutral grays.

Figure 4. The chart after using the White Balance Selector.

Figure 4. The chart after using the White Balance Selector.

Figure 5 shows a magnified section of before and after the Lightroom adjustment.

Figure 5. Natural light of my Coast HP7R (top) and the color-corrected version (bottom).

Figure 5. Natural light of my Coast HP7R (top) and the color-corrected version (bottom).

Also after clicking on the chart, the numbers on the sliders change to reflect the new white balance (Figure 6).

Figure 6. Original white balance (left) and the corrected white balance (right).

Figure 6. Original white balance (left) and the corrected white balance (right).

At this point I am not overly concerned with the actual numbers. The real information I am looking for is which way the sliders moved. Figure 6 shows us that Adobe color-corrected by adding a bunch of yellow. This is the important thing for me to note, because it means that in order to correct my flashlight, I need to do the same thing!

Fixing the Flashlight

The next step is to begin experimenting with filtration. A common form of filtration for the photographer is a thin, heat-resistant, polyester filter that’s often called a “gel.” Gels come in a staggering number of variations and are used to enhance the color of light or to color-correct it. Gels also come in different sizes, but the ones typically used for on-camera flash units and flashlights are about 1.5 by 3 inches. Figure 7 shows how this size is neatly bundled into a swatch book. For the small investment of $2.50, the Roscolux Swatchbook is must-have for light painters.

Figure 7. Roscolux Swatchbook.

Figure 7. Roscolux Swatchbook.

Knowing that I have to cancel out blue, I open my swatch book and find a common gel called a CTO (color temperature orange). It comes in several strengths, with designations such as 1/4 CTO, 1/2 CTO and Full CTO (the strongest). By tearing out the gels from the swatch book, I can cover the flashlight, illuminate the color chart and begin taking pictures of the color chart again.

After making some test shots, I load them into Lightroom and visually compare the charts with the original and color-corrected versions. After several experiments I find that the 1/4 CTO does a pretty good job of neutralizing the blue cast.

However, I also want to add a bit of warmth to my light, so I up the strength of the CTO to 1/2. This works well, but it does impart a bit of green, so I add a 1/8 minus green filter which adds some magenta. Figure 8 shows the color-corrected chart on the top and the chart illuminated by my Coast HP7R gelled with Rosco 1/2 CTO and 1/8 minus green filters.

Figure 8. Color-corrected chart on top, filtered version on the bottom.

Figure 8. Color-corrected chart on top, filtered version on the bottom.

This test is by no means superscientific, but it gets you in the ballpark. Taking the time to experiment with a few filters will allow you to paint with confidence out in the field and will save you a ton of time color-correcting in Lightroom and Photoshop. Of course, if you use the Coast HP7R, you don’t have to run any tests at all, because I just told you the results! A Roscolux 1/2 CTO and a 1/8 minus green combo work nicely. It’s also a good combination for the lower-powered Coast HP5R, another of my favorite flashlights.

Putting This Into Practice

Once you’ve determined which gels you need, it’s time to attach them to your flashlight. This can be accomplished in many different ways. The easiest is to simply fold the gel(s) over the end of the flashlight and wrap a rubber band around it. This certainly works, but is not overly elegant and may result in lost or damaged gels over time.

For my gels, I purchased the $4.99 LF100 Lens Filter Kit from Coast. Figure 9 shows how the rubber bezel cover can hold any of several colored or clear plastic filters that are included with the kit.

Figure 9. LF100 Lens Filter Kit from Coast.

Figure 9. LF100 Lens Filter Kit from Coast.

I used a filter from the kit to trace and cut my 1/2 CTO and 1/8 minus green filters, then simply taped them to the clear filter. Voila. Perfect color and no hassle of taking filters on and off out in the field. The LF50 Lens Filter Kit does the same job on the smaller HP5R flashlight.

Figure 10. A rusty fence light-painted with just the Coast HP7R (left), and with the same flashlight modified with the 1/2 CTO and 1/8 minus green filters (right).

However, while my test has provided the desired color from my flashlight, it works only when I am using Direct Sun (daylight) white balance. In Part II of this topic, I’ll address the issue of filtering your flashlight when you are using the common nighttime white balance setting of 3200 K.

See the continuation of this article: “Level Up With Light Painting: Correcting the Color of Your Flashlight (Part II).”

Learn more techniques from Tim Cooper’s book The Magic of Light Painting, available from Peachpit.