Terra Galleria Photography

Polarizing Filters and Vignetting on a Wide-Angle Lens: Corrections in Processing

Modern zoom lenses are quite amazing compared with what was available a few decades ago. A lens such that the Sony FE 24-105mm f/4 G OSS (reviewed here) offers a great combination of sharpness and versatility in trans-standard focal lengths, all in a relatively compact package – consistent with the appeal of their A7 series cameras, Sony emphasizes that this lens is the smallest and lightest of its class.

However, compromises still have to be made for such lenses. In typical fashion, Sony designed the lens with a tight image circle, meaning that the area illuminated by the lens barely covers the full-frame sensor. This results in strong vignetting, the darkening of corners and edges compared to the image center. To keep the lens compact, a 77mm filter thread was chosen, instead of 82mm. As a consequence, corners are further darkened by a thick filter as the filter cuts into the field of view of the lens.

The problem is particularly noticeable with a polarizing filter, because even a thin polarizing filter is still quite thick compared with other filters. Here is a typical example at 24mm, f/11, from the Cadiz Dunes of Mojave Trails National Monument:

The image was photographed on the Sony FE 24-105 f/4 lens on the Sony A7R2 with a Tiffen filter which, at 7.7mm, is relatively thin – by comparison, my B+W and Heliopan polarizing filters are respectively 11mm and 12.7mm thick. This seems to contradict Ken Rockwell’s statement about that particular lens:

There’s no need for thin filters. Go ahead and use your standard rotating polarizer and grad filters. I can use fat 77mm filter and get no vignetting at 24mm on full-frame
It’s not that Rockwell’s website is “a work of fiction, entirely the product of [] imagination and personal opinion”. Rather, he shoots exclusively in JPG, in which case by default the camera automatically corrects vignetting by applying a profile. For example, on the Sony there is a setting “Lens Comp.” and within, the default for “Shading Comp.” is “Auto”. With that default, the image that you see in the viewfinder or LCD has the correction applied, so you don’t even see the full extent of the vignetting. Personally, I prefer to turn “Shading Comp.” to off to see what I get in the RAW file, because such a correction is not applied to a RAW file. With “Shading Comp.” off, the vignetting within the bare lens (example here) is barely noticeable, however, the vignetting caused by a polarizer is evident.

Provided that Lightroom has a profile for your lens and camera combination, it does the correction automatically on the RAW file much the same way as the camera corrects JPGs. “Enable Profile corrections” in the Lens Corrections panel is checked by default. By the way, acquiring the FE 24-105mm forced me to upgrade my operating system, which broke many applications! For some obscure reason, the version of Lightroom I was using was not supporting that particular lens profile, so I needed to upgrade to Lightroom Classic CC. In turn, Lightroom Classic CC was not supported by the version of Mac OSX I was running.

By default, the profiles corrections consist of both distortion and vignetting (both sliders are at 100%). We are concerned here with the vignetting, so let see what happens if we move the “Distortion” slider to 0% and keep “Vignetting” at 100%:

This was not too helpful!

Getting “Distortion” back to its default 100% definitively improves things. This tells us that the improvement is due to the corners being cropped by the distortion correction rather than being brightened by the vignetting correction. If you like to compose tightly to the edges and not crop like I do, this can alter your compositions. Parts of the image’s exposure are also affected, with fewer highlights being recoverable, as can be seen in the upper corner.

For all those reasons, I leave “Enable Profile corrections” off in my own default, and instead apply it on individual images on a case-by-case basis. Most of the time, those corrections are not necessary. A slight amount of vignetting can be desirable, as it helps keep the eye in the image center, and distortion is only noticeable in landscapes with a straight horizon line. Another problem with applying those corrections by default is that they slow down Lightroom quite a bit.

By the way, you can notice in the Lightroom screenshot that “Remove Chromatic Aberrations” is checked. By Lightroom defaults, it is not checked, although of the two boxes that is the one that I enable in my own defaults because there is no downsides to it. In my opinion, Adobe got it wrong with their two defaults here.

Even with the distortion correction, dark corners are still somehow present and distracting. To finish the image, I needed to crop manually to get rid of them.

The other problem with using a polarizer on a wide-angle lens is that this can result in uneven polarization of the sky, since the polarization depends on the angle relative to the sun. The polarizer’s effect is strongest a 90 degrees from the sun. In the image, the polarization is most intense at one-third of the frame which was at 90 degrees, and as you get over or under that angle, the effect is reduced. The overall effect is a darker blob, which is quite noticeable in a cloudless sky. It is quite easy to miss that effect in the viewfinder. In this case, I previously had the zoom set at a longer focal length, where the polarizer was just fine, and didn’t pay enough attention as I set the zoom to 24mm. Be careful with polarizers on wide-angle lenses!

Totally fixing the uneven sky in processing is very time-consuming, since it involves rebuilding the sky in Photoshop – this discussion gives an idea of the techniques involved. I quickly mitigated the problem in Lightroom by reducing the contrast and brightening shadows on a gradient selection of the sky, resulting in the finished image above.

Utilizing Weather in Shenandoah

I have found the adage “Bad weather makes for good photographs” generally true. Cloudless days are not what I look forward to for daytime photography. There are two approaches to finding favorable weather conditions for landscape photography. You can go to a location based specifically on the weather forecast – the best is little-known Meteoblue because it includes cloud cover at different altitudes. Instead of looking for weather, you can wait for it. I somehow used both approaches on the same day in Shenandoah National Park.

I’ve heard some photographers and workshop leaders drive hundreds of miles in a day to place themselves at a scene with “epic” light for a sunset. I am not a big fan of that approach. When I am out in nature, the experience of enjoying the environment is paramount. Spending hours rushing in a car is not a way to do it. Although I admire those epic pictures, I feel that there is more to nature than that, and I’d be missing a chance to make those discoveries if I was focussed only on getting the epic, pre-conceived, picture. Rather, my approach in looking for weather is to make smaller adjustments to my itinerary based on weather conditions, as well as looking for subjects appropriate for the weather.

The day had started sunny, but as I drove down the Skyline Drive in Shenandoah National Park and the road climbed to higher elevations, clouds started to roll in, obscuring views. I abandoned my plans for a long hike to a mountaintop, switching my interest to the forest. I love the depth and atmosphere that fog brings in any forest, and the thicker, the better.

Any place in the park is a good starting point to explore the forest. Whenever I encountered a section of dense fog along the drive, I would look for the nearest pullout or trailhead. Opposite the Little Hogback Overlook, beautiful ferns cover the ground, and so do they along the section of the Appalachian Trail accessible from the Hogback Overlook. When the fog started to dissipate, I’d go back to the car, and then keep driving until another area of dense fog.

By the time I arrived at Big Meadows, the rain was quite heavy. Rainy weather is excellent for photographing in the forest, but having photographed in rain with the benefit of fog earlier in the day, I didn’t feel like venturing in the downpour. I went to the Big Meadows Lodge for a picture of the inside. There, I found a cellular signal, which allowed me to figure out that the rain might stop. If the weather was to break, Big Meadows was a good place to be as, like the name implies, it is only one of the large open areas in the park. It is not a natural meadow but rather was cleared by the early settlers who were evicted to make room for the national park. While most of the park has been allowed to revert to a wild state, the NPS has chosen to maintain Big Meadows in its historic condition. Hawksbill, highest peak in the park, wasn’t too far, but the sound of thunder made it clear hiking high would be too risky of a proposition. I hung around and got out when the rain started to subside, and almost like on cue, the rainbow appeared just before sunset time.

Photographing Waterfalls in Whiteoak Canyon, the scenic gem of Shenandoah National Park

Shenandoah National Park is a long and skinny park. The Skyline Drive runs its entire length of 105 miles. For most of it, the road is never more than a few miles from the park’s boundary on both sides. For this reason, besides the Appalachian Trail that closely parallels the Skyline Drive, there are few hikes in the park that aren’t short. The two best ones are the Old Rag Loop (8.8 miles, 2,400 ft elevation gain) which offers great scrambling and views, and the Whiteoak Canyon/Cedar Run loop (8 miles, 2,750 ft elevation gain). The later combines two hikes: the Whiteoak Canyon, a steep gorge with six waterfalls, has been called the “scenic gem” of Shenandoah, and along Cedar Run, two more waterfalls can be seen (NPS map).

Sony A7R2, polarizer, 24-105@57mm, 1/6s at f/8.0, ISO 200

During my autumn trip to Shenandoah, water levels were quite low for a waterfall hike, but last spring, conditions looked wet enough. Stopping at the visitor center for unrelated information, I thought I might as well ask for trail conditions. I was glad I did, when I was told that there was so much water that the connector between Whiteoak Canyon and Cedar Run was entirely flooded. Starting from Cedar Run, I might have never made it to Whiteoak Canyon. Instead, I changed my plans to hiking Whiteoak Canyon as a out-and-back hike. Always a good idea to do a last minute check with the rangers!

Sony A7R2, polarizer, 24-105@47mm, 1/3s at f/13, ISO 100

The Whiteoak Canyon Trail was quite wet from the start. Hiking became easier after I gave up on trying to keep my feet dry by avoiding the puddles – I had packed two pairs of shoes for my trip. The trail at first doesn’t follow the river, and the sun was still quite bright, so I didn’t photograph much until the bridge over the Robinson River, about two miles from the trailhead. Those bridges always provide interesting vantage points. I waited for a bit of cloud cover to soften the light and reduce the bright spots. Stream and waterfall images are all about the flow, and there is nothing like bright spots and shadows to interupt it. Compared with the photograph I made on the way back at dusk, the afternoon image with some hints of sunlight was more lively. Always a good idea to photograph in different light conditions!

Sony A7R2, polarizer, 24-105@39mm, 1/5s at f/16, ISO 100

After the bridge, the trail mostly followed the Robinson River, providing numerous compositions. Despite the length of the hike, I made sure to carry my tripod to be able to use a range of shutter speeds because water would be a primary subject. Photographing backlit made the leaves glow a fluorescent green. Since I wanted a slow shutter speed to blur the water, I had to wait for a lull in the breeze so that the leaves would not be blurred.

Sony A7R2, polarizer, 24-105@55mm, 1.3s at f/11, ISO 100

Although the cascades and waterfalls over Robinson River are the main attraction in Whiteoak Canyon, because of the wet conditions, water was flowing everywhere (including on the trail), creating ephemeral waterfalls of more delicate beauty than the main stream. Finding it more exciting to try and capture the transient, I made sure to look around.

Sony A7R2, polarizer, 16-35@23mm, 1/13s at f/11, ISO 100

Although a (variable) neutral density filter is ideal for photographing streams, it is not necessary. When the water is not in direct sunlight (a situation to be generally avoided), using a polarizing filter and stopping down gets me shutter speeds which are slow enough to blur the water. By varying aperture and ISO, it is possible to get a range of shutter speeds. Digital photography is particularly great for photographing water because you can experiment with shutter speeds and get immediate feedback. Some scenes look better with the water entirely smoothed, for some it is preferable to freeze the motion a bit, and often a combination of both in a single frame gives the most dynamic result.

Sony A7R2, polarizer, 16-35@16mm, 0.6s at f/8, ISO 250

As with all river hikes in Shenandoah National Park, you start from the ridge (elevation 3,385 ft), and the sound of the waterfalls entice you to hike further and further downhill. Remember you’ll have to work your way up. My favorite part of Whiteoak Canyon was an off-trail point at about three miles, elevation 1,750 ft, where several branches of the stream converge, forming a striking wall of waterfalls. In this photograph, the role of the polarizer was to increase contrast between the whitewater and the darker, more smooth sections of water, as well as increase the saturation of the leaves, rather than slowing down the shutter. Instead, at base ISO it resulted in a shutter speed which was a bit too low for the effect I preferred, so I raised the ISO.

Sony A7R2, polarizer, 16-35@16mm, 1.3s at f/8, ISO 100

On my way back, I detoured again to a rock ledge a short distance downstream from the bridge that provides a fine and vertiginous view of the upper falls, the only such large scene along the trail. In the afternoon, the waterfall was in the shade, but the surrounding trees and cliff were sunlit. Now the scene was softly lit, with a bit of fog providing some atmosphere. Even though a loop can be a more satisfying experience, revisiting a scene on an out and back trail even within a few hours pays.

Sony A7R2, 16-35@22mm, 25s at f/4, ISO 800

Further back, I had spotted a smaller river scene along the trail, but the afternoon light wasn’t favorable. Since it was now dark, I was able to illuminate the scene with a flashlight (described here) creating even light that appears at first like sunshine, but without the distracting shadows that would have resulted from sunshine. Darkness is not a reason to stop photographing.

How to Charge Digital Cameras in the Field

Modern digital cameras can go through batteries quickly. One can just carry enough camera batteries to last for an entire short trip – I own more than a dozen. If you stay under a roof at least every other night, plugging into AC power to recharge your batteries is easy. Otherwise, another way to charge those batteries is needed. In this article, after surveying all available options, I detail the solution I settled on after trying many, down to brand and models.

In 2016, I flew in by floatplane and spent five days at Brooks Camp in Katmai National Park in Alaska. Without access to AC power nor a car, I relied exclusively on external batteries to recharge camera batteries for my two power-hungry mirorless Sony A7R2s.

Charging from the car

On a trip where you drive abundantly each day, you can charge camera batteries using the car 12V DC power from the cigarette lighter. The manufacturer-supplied camera battery charger often operates only on 110V AC, and you could use a power inverter to obtain 110V power from the car’s 12V. Besides the fact that you are converting 12V to 110V and then back to a lower voltage in the camera battery charger, those devices can heat up quite a bit and are not the safest to use. The alternative is to buy a third-party camera battery charger that operates from a lower voltage, either 12V or a 5V (USB). I’ve used both and have a strong preference for USB as discussed later. If I need to recharge camera batteries quickly, unless I am driving non-stop, I will plug them to an external battery rather than to the car’s 12V outlet. This allows camera batteries to recharge even during stops. At the same time, I recharge other external batteries that are not in use on the car’s 12V outlet.

Left to right: dual and quad cigarette lighter to USB adapters, power inverter.

Charging while camping

Private campgrounds often provide AC power. In general, public (including National Park Service) campgrounds do not provide AC power at regular campsites. It is found in the bathrooms, where the plugs are meant for shaving, not recharging devices. Charging batteries from your parked car runs the real risk of depleting your car’s battery and leaving you stranded. Mitigating this risk by leaving the engine running consumes gas and can be a nuisance. Solar could work if you have a campsite set during the day, but is not dependable since efficiency depends on weather conditions. With no access to AC power, the best way to recharge your camera batteries is from external batteries. Depending on the trip I carry anywhere between two to half a dozen 10,000mAh 5V batteries.

The Kendesnii Campground in Wrangell-St Elias National Park, Alaska, where we stayed for three nights, has great views, but no electricity.

Multiple-purpose batteries v. Single-purpose batteries

I always leave in the car a Bestek battery primarily advertised as a jump-starter that works extremely well for that purpose. It is also advertised as a power source. However, although according the manufacturer’s stated capacity it should be able to charge at least 6 Sony batteries, it barely charges 2. The discrepancy is even worse with a Tekkeon battery that can deliver almost any voltage from USB to the 19V needed by laptop computers. I used to carry that one in all my travels for its versatility, before discovering how inefficient it is for charging. If a battery has to support a variety of loads ranging from jump starting cars to charging cellphones or cameras, it is difficult to design a high efficiency power converter across such a wide range and to find the perfect battery technology to perform well in every case. For example, to jump start a car, you need to deliver huge amount of current (in the order of a few hundred Amps) for a short time. To charge a camera battery, you need to delivery mA for hours, at the opposite end of the application spectrum from jump starting a car. The bottom line is that the most efficient batteries are those that deliver a single voltage and are meant for a single type of use (charging other batteries) and nothing else.

12V v 5V (USB)

Which voltage to choose? The fact that it is easier to convert voltage down than up favors the batteries and chargers that use the lowest voltage that is common, which is the 5V of USB-powered devices. Not only they are more efficient in use, but also having the same input and output current makes things simpler to manage. The three 12V external batteries that I own need to be charged by plugging into AC power, whereas all USB external batteries can be charged from AC, 12V, or USB. USB ports are ubiquitous, being found in computers, recent cars, and solar panels. With the proliferation of mobile devices that are all USB-charged, external USB batteries are much more common than 12V external batteries, and available in a variety of shapes and sizes to fit any situation. In addition, most modern cameras can charge their battery if you plug a USB cord, so you always have a USB camera battery charger with you. The only reason to use 12V external batteries would be if you have devices that are 12V-powdered, which is a standard in the video world, and is also used by some motion-control apparatus.

12V power kit. Left to right: Dynamic Perception 12V battery (2700mAh, 194g), Tekkeon battery with extender (7200mAh, 810g), Wasabi Power Sony NP-FW50 charger.

Choosing USB external batteries

I have now standardized on 5V power. As illustrated by the example above, battery manufacturer specifications are not to be trusted. The only way to find one that works reliably is to test. A meter helps by displaying the total energy delivered. After testing several brands and models, I have settled on the 10,000 mAh Anker external batteries. I’ve been told that they use cells from Panasonic which makes some of the highest quality Li-ion batteries in the industry. They deliver about 90% of the specs (some others have been as low as 25%, and even Anker’s 13,000 mAh battery whose dual USB ports are useful, wasn’t as efficient), have some of the best capacity to weight ratio of any external batteries, and are cost-effective. If you need a more rugged battery the Goal Zero devices (such as this one) have very nice features but are quite more expensive.

Charging camera batteries from USB external batteries

You’ll have to buy a third-party USB camera battery charger. I use the OAproda NP-FW50 for Sony which costs less than $10, and equivalent products are available for other camera brands. They are so much more versatile, since you can use them with AC, 12V, and USB, and a side benefit is that they are smaller and lighter than the manufacturer-supplied AC camera battery charger. By the way, the same is true of other devices as well, for instance USB-powered headlamp, lanterns, and AA/AAA chargers, and now I favor those that can be recharged by USB over those that require AC. You’d think that a USB cable is a USB cable, but their choice matters, the shorter and thicker the better, and not only for bulk reduction. With a long and thin USB cable, you could lose as much as 40% of the power. There are also several dual camera battery chargers available, which are slightly more compact than two single camera battery chargers and more convenient as they require only one USB connection instead of two. However, carrying two single camera battery chargers provide more redundancy, should one of the devices fail.

Sony NP-FW50 chargers. Left to right: OAproda (USB, 30g), Wasabi Power (12V, 70g), Sony OEM (AC, 85g).

Recharging USB external batteries

To charge USB batteries (external or camera) from AC power, you need a AC-USB adapter. Although all of them could work in a pinch, their performance varies as much as the external batteries performance. I’ve found the Anker 6-port charger to work very well, maybe because the manufacturer could optimize it operate with their own batteries. To charge USB batteries from 12V DC, one quad cigarette lighter to USB adapter is normally enough for me, and it is not much bigger than one with a single outlet. Here is the power kit with which I normally travel:

5V/USB power kit. Left to right: OAproda Sony NP-FW50 chargers, quad cigarette lighter to USB adapter and iPhone cable, Anker 6-Port USB Wall Charger with replacement short power cable, USB cables, Anker 10,000mAh and 13,000mAh 5V batteries.

Photographing Cataloochee, the quieter side of the Great Smoky Mountains

With more than 10 million visitors per year, Great Smoky Mountains National Park is the most visited of the national parks, and its most popular area is Cades Cove which receives over 2 million visits per year, more than many large entire parks. Cades Cove is so popular because it has a bit of everything for everyone: historic structures, wildlife, and pastoral landscapes. Fortunately, at the opposite end of the park, Cataloochee offers a smaller version of Cades Cove, one that is considerably quieter. Follow me on a quick tour of Cataloochee and learn the technical choices behind the photographs.

Remoteness has so far preserved Cataloochee’s tranquility. The quickest access, via Cove Creek Road off US 276, is further away from a gateway town than any other significant park entrance, and involves a steep, narrow, and twisting road, some of which is unpaved. The unpaved road via Big Creek is even longer and more rough. Although all the roadside sights can be easily seen within a day, I stayed at the campground. It was not filled up, but note that you need to reserve your site by phone or online, which means prior entering Cataloochee since there is no cell signal in the valley.

There is only one clear view of the mountains in the Cataloochee area, at an unnamed overlook located shortly after the point when the road becomes paved again. The overlook is north facing, so both sunrise and sunset create side lighting. With mostly cloudy skies, the light was weak, but I thought the images I made after sunset made the most out of it, as the ridges were better delineated by the soft backlight and the sky momentarily acquired a bit of color.

An unexpected reward for staying at the campground was to find there a nicer cluster of Mountain Laurel than any I’d seen on the trails. Picnic tables were all around, but by moving in close and pointing the camera up, I excluded them. Is that still a truthful photograph? I chose the moment when the blooms were in the shade while the trees behind were sunlit. Like other small subjects, flower close-ups almost invariably work better in soft light, and if you photograph at a close distance with a wide-angle lens, the foreground becomes a close-up. On the other hand, if the trees had been in the shade, their darker leaves would have let the sky, which was inevitable as the camera was pointed up, create distracting bright spots. The potential downside of this choice of light is that the blooms could be too dark. In the old film days, I would have added a bit of light to the blooms with fill flash, but I knew that Lightroom would easily let me brighten them.

Like Cades Cove, Cataloochee features historic meadows encircled by mountains. This large but relatively featureless landscape needed strong light and shadows to define its structure. I photographed in the late afternoon, as the shadows were moving into the valley, but before they became overwhelming.

The Cataloochee area was once the most populated area in what became Great Smoky Mountains National Park. Nowadays it features eight historic sites easily accessible, only two fewer than Cades Cove. I wanted to give a sense of place for my photograph of Caldwell’s House by including the river and footbridge. As is often the case, having the river in the shade turns it into a mirror, whereas direct sunlight suppresses reflections. With the low late afternoon sun, shadows from the trees generated a confusing patchwork of shadow and light, so I waited for the meadows and house to be entirely in the shade.

Shade is a foolproof light for photographing a close-up scene, and I am always ready to make my own, even at midday. However, I noticed that branches of a nearby tree were filtering the sunlight enough to eliminate dark shadows while preserving a bit of direct light, resulting in beautiful illumination. Following the light, I looked for a composition and found those ferns and leaves, whose textures and colors were accented by the sunshine in a subtle way.

Besides looking for close-ups, I busied myself at midday by photographing inside the historic structures, where it becomes all about geometry. The images are not as straightforward as they seem, and necessitated careful adjustments with a shift lens. Fortunately, I could adapt the excellent Canon 24mm TSE to use on my Sony A7R2. For the schoolhouse above, notice how I was able to keep the shape of the back wall a rectangle rather than a trapeze, although most of the scene is located on the right side of the camera. This was made possible by shifting the lens towards the right, rather than rotating the camera. Similarly, for the barn below, notice how, with the central point of perspective located approximately 1/3 up the frame, you see more of the interesting ceiling than of the floor, yet vertical beams have remained parallel. This was made possible by rising the lens, rather than pointing the camera up. The Sony A7R2 almost handled the extreme contrast between the sunny outside and the dark inside with a single exposure, but for a bit more highlight detail, I merged two exposures in Lightroom in each case.

Firefly Variations

In this post, I revisit a firefly photograph in some detail, first comparing it to a similar image made with a different technique, then showing its components images to highlight firefly specifies within.

Single exposure v. Digital composite

I mentioned previously that there are two approaches to photograph fireflies together with the forest, a carefully timed single long exposure or a digital composite from several short exposures. Even if you are not going to photograph fireflies any time soon, note that those considerations also apply to star trails or even light trails from cars at night. The composite approach is safer for several reasons. The first reason is that it makes it possible to use a base exposure while there is still light, so that one can avoid high ISO and a long exposure, a combination particularly problematic, as taken individually, each of them is already the main cause of noisy images. The second reason is that besides noise, a single, long exposure is vulnerable to incidents such as someone shining a light. With several short exposures, you have the option of simply not using the affected frames, whereas a single exposure could be ruined beyond repair. The third reason is that it makes it easier to control the brightness of the final image. If you do not time well a single exposure and it is too long, the forest may end up too bright relative to the fireflies, which would ruin the shot. With separate exposures for the forest and the fireflies, you can easily tune their relative brightness.

With the lens set wide open at f/1.4, I focussed at infinity. This resulted in the light from the fireflies forming an out of focus disc of size inversely proportional to their distance, which helped convey the sense of the depth in the forest I had in mind for this photograph. Unlike for others, I had chosen a slightly elevated viewpoint to this effect. However, in the single exposure frame below, some fireflies had flown very close to the camera, resulting in blobs of light that could be distracting.

Single frame, Sony A7R2, Rokinon 35mm, 8 min at f/1.4, ISO 800 (Click image to enlarge)

For the digital composite, I selected 13 frames, leaving out those with distracting fireflies, resulting in a similar total exposure time. I loaded them as layers in a stack by using “Tools > Photoshop > Load Files into Photoshop Layers” in Bridge (you can also do that directly in Photoshop with “Files > Scripts > Load Files into Stack”). Then in the Layers palette, I selected all the layers and changed the blending mode from “Normal” to “Lighten”. The “Lighten” blending mode creates a composite by taking for each location the brightest pixels in the stack, and since the fireflies are brighter than the forest, I was done. I tried to use a brigher base exposure for the forest, but eventurally prefered the darker exposure from the first frame of the stack.

Digital composite, Sony A7R2, Rokinon 35mm, 13 frames, 30 sec at f/1.4, ISO 1600 (Click image to enlarge)

I’d appreciate it if you would let me know which of the two is your favorite? Does it matter that a photo was captured as a single exposure, or does only the result count?

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Photinus frontalis v. Photinus carolinus

Another benefit of making several short exposures is that the individual frames reveal the light patterns of different firefly species better than a single long exposure or a composite does, even if the later is more impressive by virtue of the myriad of lights captured. In the two photographs above, the fireflies appear to be all over the place, blanketing the forest. However, the 30-second exposures let you see the long light trails of the Mammoth Cave National park fireflies with evenly spaced blinks like the Photinus frontalis species. The animated GIF below consists of the 13 frames that make up the composite.

Mammoth Cave National Park fireflies (click image to enlarge)

By contrast, the Photinus carolinus of Great Smoky Mountains National Park have shorter light trails, since they blink only 5-8 times before going dark for a period of time longer than the flashing time. This can be seen in the animated GIF below.

Great Smoky Mountains National Park Photinus carolinus fireflies (click image to enlarge)

The difference in flashing patterns was not as readily observed in the final composite image below:

Digital composite. Sony A7R2, Sigma 20mm f1.4 lens. Base exposure: 30s at f/2.2, ISO 200. Fireflies: 28 frames, 30s at f/1.4, ISO 3200

I hope that this series of posts has inspired you to go and seek these bioluminescent beauties that bring enchantment to summer evenings in the eastern forests, and has given you enough information to try your hand at photographing them. Firefly populations are on the decline, due to increased light pollution and habitat loss, so while enjoying them, be sure to thread lightly!

Part 3 of 3: 1 | 2 | 3

Synchronous Fireflies Beyond the Smokies

Great Smoky Mountains National Park was once thought to be the only place in North America where the synchronous fireflies (Photinus carolinus) can be seen. Fittingly for the most visited national park in America, the event has become very popular, as described in the previous article. During my East Coast trip this spring, I observed fireflies at two other national parks, where you can sidestep the hassle of the lottery, mandatory shuttles, lines, and crowds.

Firefly species

Large concentrations of fireflies tend to occur in humid, dark, and clean environments, and besides Great Smoky Mountains National Park, Mammoth Cave and specially Congaree National Park fit this description quite well. The synchronized fireflies found there are of a different species, the Photinus frontalis. Their flashing pattern consists of a quicker flashes at regular intervals of less than a second, which register on photographs as circles rather than the short light trails of the Photinus carolinus. By the way, in some of those photographs, esp. 10:21 PM, you could see a long light trail with a cooler hue. This is the black sheep of the firefly family, the rare blue ghost firefly (phausis reticulata) that glows the wrong color and for too long, lighting up continuously for up to minute. The Photinus carolinus‘s flashes are synchronized in the sense that they blink in unison, but they do not all go dark at the same time. Pauses in the flash pattern occur at irregular intervals. In other words, the males flash synchronously, for several flash cycles, then, one firefly will stop flashing while the other continues flashing, and then the stopped firefly begins to flash again synchronously.

Light trace of a single firefly. 9:21 PM. Sony A7R2, 35mm, 30s at f/1.4, ISO 6400

Congaree National Park

For firefly viewing, Congaree National Park has been recommended by the National Park Service as an alternative to Great Smoky Mountains National Park, and here is the park’s firefly information page. No bus nor lottery is necessary there, but it is wise to arrive early since parking is limited. The activity takes place less than a quarter-mile from the visitor center parking lot, and you can witness it along the park’s trails and boardwalks. During the 2018 firefly viewing period, the NPS has put in place a “Firefly Trail”, which goes one-way and starts from the picnic shelter, with the elevated boardwalk reserved for accessible access. The Firefly Trail is roped and is lighted by red lanterns placed on the ground so that visitors do not need to use flashlights. In order to find a viewing spot unaffected by lights, I walked along the Bluff Trail instead. I certainly don’t begrudge the hikers who shined a red light during my exposure. It was so dark in the forest that at one point, as I wanted to check something on my phone and stepped away from my camera so that its display would not affect the exposure, I found myself totally disoriented!

9:24 PM. Sony A7R2, Rokinon 35mm, 14 min at f/1.4, ISO 1600. Composited with 30s at f/1.4, ISO 6400 frame to remove light pollution from hiker flashlight

Like the Photinus carolinus, the synchronization period lasts about two weeks, at but it takes place earlier in the year and night at Congaree National Park. In 2018, The synchronous fireflies became active on May 16 and ended the first week of June. Their activity starts at sunset and lasts only about one hour. The park is also home to other species of fireflies that remain active all night, and I my camera captured a few during a time-lapse that I set next to my tent at the Longleaf Campground.

Digital composite, four frames, Sony A7R2, Sigma 20mm, 15s at f/2, ISO 800.

Mammoth Cave National Park

Maybe because almost all visitors come for the cave, Mammoth Cave National Park’s fireflies are under the radar. In fact, the NPS website’s page dedicated to insects doesn’t even mention them at all.

Digital composite, six frames, Sony A7R2, Nikkor 14-24mm @ 14mm, 30s min at f/2.8, ISO 3200.

Upon arriving at the Houchin Campground one hour before sunset, I noticed fireflies flying upwards on grassy areas while flashing a single sustained yellow light in the shape of the letter J. Since I was focused on photographing the Green River with the colors of sunset, I planned to photograph them later. But by the time the color was gone, so were those fireflies. I subsequently learned that they were the Photinus pyralis that finish displaying by 9:30. My time-lapse camera by the river captured fireflies with a light trail similar to those in the meadow in Congaree.

10:10 PM. Sony A7R2, Rokinon 35mm, 8 min at f/1.4, ISO 800.

Because of torrential thunderstorm rains in the afternoon, I ended hiking a trail quite late in the evening. As I began to notice the now familiar blink of fireflies, I rushed to my car to retrieve my f/1.4 lenses. Not expecting them there at all, I was delighted to see that the fireflies were in pretty large numbers, and synchronized too, the same way as the Photinus frontalis.

10:41 PM. Sony A7R2, Rokinon 35mm, 8 min at f/1.4, ISO 3200.

Except for a few, their flashing looked similar to them, but that species isn’t mentioned in that survey of Mammoth Cave fireflies, so I am not sure which species they were. However, sitting by myself on the trail, I for sure enjoyed the unexpected gift. After so many forest photos, I moved to capture the fireflies with the backdrop of a sink hole typical of the terrain found in the park.

11:15 PM. Sony A7R2, Rokinon 35mm, 8 min at f/1.4, ISO 3200.

A few other spots have now emerged as places to view synchronized fireflies, but I hadn’t seen Mammoth Cave National Park listed amongst them. My experience leads me to think that as you wander in the eastern hardwood forests at night, you might find the next one.

Part 2 of 3: 1 | 2 | 3

Photographing the Great Smoky Mountains Synchronous Fireflies

One of nature’s most wondrous light shows occurs during the synchronous fireflies mating season, when the bugs flash at once in a silent symphony of sparks. Synchronous fireflies exist only in a handful of places in the world, with Great Smoky Mountains National Park being the most well known. In this article, I explain how you can view the awesome event and provide detailed tips for photographing the fireflies, an endeavor that is sure to challenge your skills.

What are synchronous fireflies and how rare are they?

If unlike me, you have lived on the U.S. East Coast, you might have seen twinkling fireflies in your backyard. Now imagine the magic of seeing them flashing at once. Upon transforming from larvea into adult insects, male fireflies stop eating for the three weeks of their remaining lives. Given that short time left to attract a partner, they blink in order to court females. There are many species of fireflies that live in Great Smoky Mountains National Park, but only one, the Synchronous fireflies (Photinus carolinus) can synchronize their flashing, for reason that are still mysterious. In Fireflies, Glow-worms and Lightning Bugs, researcher Lynn Frierson Faust writes:
dense populations of fireflies are more likely to synchronize in order for the females to be able to answer the male flash (during the dark interval) and still be seen… we found that Photinus carolinous females will refuse to respond if multiple male flash patterns are presented to them randomly
The whole forest becomes similar to a giant Christmas tree, with thousands of flying fireflies flashing about six times in unison, and then going totally dark for about six seconds, and repeating again for about two hours.

9:46 PM. Sony A7R2, Rokinon 35mm f1.4 lens. 4.5 min at f/2.8, ISO 1600. +1.3 Exposure in LR

To see the firefly light show, you have to be at the right place at the right time, and that’s only a few dozen hours per year in a handful of places in the world. The Smokies display takes place only during two weeks each year, with the peak date changing impredictably from year to year, anytime from the third week of May to the third week in June. It doesn’t last all night, but only for about two hours, from 9:30pm to 11:30pm, with the most active time being the middle of this window. The images in this article are roughly arranged by time of the night. Compare the amount of fireflies in the first (9:46) and last (10:35) images – keeping in mind that the exposure time was doubled. Fireflies will not fly if it rains. If it is too damp or too cold, they will not flash. Moreover, while fireflies can be seen all over Great Smoky Mountains National Park, which is home to 19 species of which 13 flash, synchronous fireflies are found in large numbers only around the Little River Valley near Elkmont, a forming logging village and now campground, which boasts the largest population of synchronous fireflies in the Western Hemisphere. Only Southeast Asian mangrove forests have displays that rival that.

Logistics

With increasing numbers vying to witness this unique phenomenon, the NPS had to put in place strict rules and quotas, which have been evolving since 2006. Tickets sold out in minutes, so in 2017, the park began a lottery system. In 2018, the restricted period, coinciding with the mating season peak, was from June 7 to June 14 and 21,000 entered the lottery for one out 1,800 passes. Winning the one in ten odds let you park a car at the Sugarlands Visitor Center and board a shuttle for Elkmont. During the restricted period, from 4pm to 11pm, the NPS closes the Elkmont road except for shuttles and registered campers. The Elkmont Campground usually fills up two months in advance, but a few spots sometimes open due to cancellations.

9:42 PM. Sony A7R2, Sigma 20mm f1.4 lens. 30s at f/1.4, ISO 1600. +3.6 Exposure in LR

During the restricted period, almost a thousand people are expected each night in Elkmont. For more quiet, you can instead visit a few days before or a few days after the restricted period, or get a designated backcountry campsite. Note that a backcountry permit does not allow you to enter Elkmont during restricted times.

Etiquette

Flashlights, and in particular white light disrupt the fireflies. To protect them, you should absolutely use a red light. It also helps preserve your night vision – and that of people around you, a common courtesy. Many headlamps come equipped with one, and are standard equipment for night photographers. Otherwise, you can cover your light with red cellophane, provided at the Elkmont Campground and during official viewing sessions. Even a red light is quite bright in pitch darkness, and there is scientific evidence that it interferes with fireflies breeding, so minimize the disturbance by using it only when strictly necessary while walking, and by pointing it at the ground. Once you are at your spot, do not turn on your light.

You should obviously not use flash. When operating your camera, be sure to turn off or cover your LCD, which is also very bright in the dark. If you need to access your bag for gear, be sure to be able to do so without seeing anything so that you don’t have to turn on your light. Despite the official recommendations from the NPS, within a crowd, it is very likely that someone will shine a light and ruin the long exposures required to photograph the fireflies. It doesn’t take much when you are using high ISO. I noticed that the camera red light that flashes while the self-timer is activated was enough to impact the exposure of my second camera.

Locations

The most popular viewing area is along the wide Little River Trail, at the beginning of which many brought lawn chairs. On June 5, I hiked a mile on the Little River Trail and that was enough to not have anybody else around. The bugs fly about 2-6 feet from the forest floor, but the steepness of the hill on the south side of the trail spread them all over the frame.

Digital composite. Sony A7R2, Sigma 20mm f1.4 lens. Base exposure: 30s at f/2.2, ISO 200. Fireflies: 28 frames, 30s at f/1.4, ISO 3200

Because the shuttles disgorge visitors at the Little River Trailhead, and the Little River Trail is the official viewing area where rangers and volunteers direct visitors, during the restricted period, several hundreds will be found there. To avoid them, I followed the Jakes Creek Trail on subsequent nights. On June 6, less than a mile from the trailhead, I had the place to myself again, but on June 7, returning to a previously scouted spot, I had to share it with two photographers, who fortunately were disciplined and considerate.

Photography equipment

Viewing the fireflies is an awesome experience, but most visitors will have only memories of the event. This is one situation where a camera phone will not capture anything.

10:21 PM. Sony A7R2, Rokinon 35mm f1.4 lens. 11 min at f/1.4, ISO 1600. +2 Exposure in LR

It goes without saying that you need a tripod. Any camera suitable for photographing the night sky can work, but the ability to use high ISO and long exposures with little noise is needed for single-frame captures. Specialized equipment will extend your window of opportunity and provide better results. Although in the dark the bugs look quite bright to your eye, they are actually fairly faint, so a fast lens is helpful because you need enough sensitivity to record the individual flashes of the bugs. The best choice is probably a 35mm f/1.4. Unless you are at the bottom of a steep hill, a wider lens (such as the 20mm f/1.4 that I used on my secondary camera) will include portions of the sky between treetops, which create bright spots that could be distracting. The depth of field of a 50mm f/1.4 is just too small. Unless compositing, exposures way longer than 30 seconds are needed to capture many bugs, light trails, and the forest, so you will need an accessory to lock your shutter for a bulb exposure.

Photography technique

Focussing can be quite the challenge because it is dark in the woods and you absolutely don’t want to shine a light. That is compounded by the shallow depth of field of your fast lens, which will not let you have everything in focus. Focussing at infinity or at a closer distance such as the closest trees produce different effects, but after trying both I found the former to generate a better sense of depth. I recommend to try and focus before it gets too dark, and then photograph for the rest of the evening with that focus setting. A tip of Sony users: the focus ring like is just an electronically coupled actuator, so taping it isn’t useful. If you happen to change a battery, the lens will reset its focusing point, so it is essential to start the evening with a full battery if you don’t want to loose your pre-set focus.

10:30 PM. Sony A7R2, Rokinon 45mm f1.4 lens. 27 min at f/1.4, ISO 3200. +0.7 Exposure in LR

To capture the forest and many fireflies, there are two approaches to exposure. The first one consists of making a single, very long exposure. Besides its purity, it has the advantage of working at any time of the night, with settings in the range of 8-30 min, ISO 1600-3200, f/1.4. The drawback is that long exposure (dark frame) noise reduction will need to be turned on, which will render your camera inoperable for double the exposure time, and even though the camera noise might still be excessive. The second approach is to make a low ISO base exposure of the forest while there is still some light, then keep your camera in place, make several exposures for the bugs, and blend them all. This approach is safer, but you will be hard pressed to make more than one such composite per night.

I have included the camera technical data and start of exposure time, but that alone would be misleading. More often than not, I didn’t come up with the optimal exposure and ended up I brightening considerably the frame in Lightroom – something that is possible with the Sony sensors even at high ISO with noise cleaning quite well in LR. I’ve therefore provided the LR exposure compensation so that you are armed with all the information you need. For reference, on June 7, sunset time was 8:48 PM.

My best tip for photography

The core of the photograph is a forest scene, and no amount of bugs would save a poor composition. I would prefer to get the composition nailed before it gets too dark to see anything. But before it gets dark enough, I cannot know if many fireflies will be active within the composition. Activity varies wildly even within a small area. On the second night, I composed a scene with a stream, since I feel they constitute the essence of the Smokies, and waited. However, by 9:45 pm, not a single firefly had lit the area. I realized that it was a low activity spot – from what I have seen, fireflies don’t seem to frequent riverbanks too much. In a hurry, I looked for a spot with activity and since by then it was too dark to see, I used 6-figure ISO exposures to compose by trial and error. This resulted in the two previous images (10:21 and 10:30).

10:35 PM. Sony A7R2, Rokinon 35mm f1.4 lens. 11 min at f/1.4, ISO 1600. +1.8 Exposure in LR

Fortunately, I learned that the active spots are consistent night after night because activity depends on conditions such as soil composition and plant cover that do not change. Knowing that, after scouting on a previous night for the most active spots as I walked down the trial, I was able to come and set up a pre-dark composition which I knew would have plenty of bugs in it. Even a 30s exposure (9:42) captured quite a few. By the time activity was in full swing, a relatively short exposure of 11 minutes was enough to fill up the frame with lights.

Part 1 of 3: 1 | 2 | 3

New LED Lights for Stationary Light Night Photography

In the past few years, progress in LED lighting has resulted in devices that offer significant advances for night photography. Find out why you should photograph at night with stationary lights rather than light painting, and read my review of my new preferred lights for that purpose.

Cannonball concretions, Theodore Roosevelt National Park, 2013. Canon 5Dmk3, Nikon 12-14, 30 sec. at f/2.8, ISO 3200. Lighted by Rayovac Sportsman lantern.

Advantages of Stationary Light compared to Light Painting

The well-known method of illuminating parts of the landscape at night is “light painting”. You move a hand-held light during a long exposure to light up large areas that could not be illuminated with the narrow beam of the light if it was fixed. Although it is convenient to deploy, requiring just a flashlight and no setup, it has many drawbacks. From a photographic point of view, results cannot be visualized, predicted nor repeated exactly. It is difficult to guess how long to shine the light on each part of the subject. You also need “painting skills” to overlap each stroke to produce even light, and in most case the illumination won’t be uniform. From an experiential point of view, the bright light impairs your night vision, creates light pollution, and bothers others who come to photograph or just marvel at the night. For the later reasons, in 2017, Arches National Parks, Canyonlands National Parks, and Grand Teton National Park took the step of prohibiting light painting – although only for workshops with the first two.

The alternative to light painting is to use a stationary light, propped on a tripod, a rock, or a tree. I have favored that technique for many years because it eliminates all the drawbacks of light painting and also works for timelapse. Because the light is stationary, its illumination accumulates over a long exposure, so one can use a dim light level, comparable to moonlight. This is at least one order of magnitude less bright than the lights typically used for light painting, and much less intrusive. In April 2018, Arches and Canyonlands officially approved “using a low level light panel that emits extremely dim constant lighting” for workshops.

Limitations of older lights

On a moonless night, typically the light level I’d aim for on the subject is comparable in intensity to quarter moon, while a full-moon night would require a light level maybe ten times brighter. The Rayovac Sportsman lantern that I described in Lights For Night Photography, typical of that generation of camping lanterns, offered only the choice between two light levels, and even the lowest one was often too bright. To control the light intensity on the subject you had to move the light closer or further, or to wrap light absorbing materials around the lantern. In addition, as pointed out in that post, the LED lights were too cold, requiring a conversion filter. The lantern was also relatively bulky and heavy, at 31 ounces with batteries.

In the interleaving years, new LED lights have emerged on the market, and they represent significant advances for the night photographer. In this post, I will review the three that I currently use.

Left to right: Rayovac Sportsman lantern with added gel (for size reference), Goal Zero Lighthouse Mini Lantern, Goal Zero Lighthouse Micro Flashlight and Lantern, HDV-Z96 light panel

Lighthouse Mini Lantern

The Goal Zero Lighthouse Mini Lantern brings the following major improvements:
  • Continuously adjustable intensity from 210 lumens to 7 lumens
  • Choice of 360-degree or 180-degree illumination (the later saves batteries)
  • Warm (3500K) light
  • Rechargeable via built-in USB cable (battery lasts 4 hours at brightest setting up to 500 hours at lowest setting)
  • Can provide power (3000mAH) to recharge devices such as a phone via USB outlet
  • 8.4 ounces with battery
As additional features, the lantern uses an interchangeable (unfortunately proprietary) battery, and for support, it features a built-in hanger, folding legs, tripod hole, and a magnet.

Lighthouse Micro Charge

The Goal Zero Lighthouse Micro Charge Flashlight, Lantern and USB Recharger retains the essential features of the Lighthouse Mini Lantern: continuously adjustable intensity from 150 lumens to 7 lumens (via single button, not as precise or convenient as the Mini’s dial) 360-degree or 180-degree, warm light, rechargeable via built-in USB plug, 2600mA charger.

Best of all, its small size and weight (3.2 ounces) means that it stays in my bag all the time. For instance, I used it for the unplanned two night images in Berryessa Snow Mountain National Monument. You can easily carry several for multiple light set-ups. The Lighthouse Micro Charge lacks the additional features of the Lighthouse Mini, but instead can be used as a flashlight (120 lumens). Pared down models without the flashlight (Micro) or charger feature (Micro Flashlight) are also available at a slightly lower price, but I prefer the versatility of the Lighthouse Micro Charge.

Goal Zero Lighthouse Micro Charge and Lighthouse Micro Flashlight

Z96 Panel Light

The only real drawback of lanterns is that they are less bright than the light painting flashlights, which can be an issue with distant subjects. Light panels solve this issue with an array of LED lights. Not only they are brighter, but also they produces a beam of about 65 degrees that concentrates the light more than the lanterns, but is still much wider than flashlights. They are quite a few LED light panels around, as they make great video lights – a market certainly larger than night landscape photography. I’ve found the Z96 panels a good compromise between brightness and portability. Their array consists of 96 (16 x 9) LED lights.

The Z96’s light intensity is continuously adjustable by dial. The unit comes with a warming front filter and a diffusion filter that attach magnetically, a tripod hole, and a removable hot-shoe bracket. It is powered by 5 AA batteries, and lasts about one hour at full power. The unit measures 5 x 1.8 x 3″ and weighs 12.5 ounces with batteries.

The F & V Lighting Z96 UltraColor LED Video Light has a high color consistency (as measured by CRI), and a low power warning circuitry that let you know by blinking that the batteries do no longer have enough power to sustain the current output and that the light will get dimmer. The HDV-Z96 96 LED Light Kit (deceptively branded “F&V”) lacks those two features but otherwise works well for half of the price.

F&V HDV-Z96 96 LED Light Kit with filters and bracket

Conclusion

I hope that this article has convinced you that stationary lights are the way to go for night landscape photography, both from a technical and ethical point of view, and that you’ll find the reviews of my favorite tools useful. Please share with other readers any other alternatives you are using.

Cottonwood Spring Oasis, Joshua Tree National Park, 2018. Sony A&R2, Sigma 20 f/1.4 Art, 15 sec at f/2, ISO 3200. Lighted by Lighthouse Mini Lantern.

Quick Processing Tip: White Application Background

There is no denying that photos look great on a computer screen, because of the transmissive nature of it, like a slide or transparency. However, in an all-digital workflow, it is all too easy to produce images whose tones are too dark. Often, photographers who do not often make prints realize that their images are too dark only after printing them, and in my experience, this is the main source of disappointment with prints. Overly dark images have less general appeal. This is not a matter of technical knowledge, but rather having a proper context to evaluate images. In this post, I’ll provide an easy-to-implement tip that has helped me much.

Rather than recording the actual light intensity like a camera, the human visual system relies on context and adaptation to make judgments of brightness. This results in a number of counter-intuitive phenomena, called optical illusions, that have been well-documented by perception psychologists. Here is one such example: which of the two areas of the central grey bar, marked A and B, is brighter?

The answer is that despite appearing to exhibit a gradient, the central grey bar is a uniform 50% grey, and therefore A and B have the same brightness. A appears brighter because it is surrounded by darker values. The lesson here is that if your surround your image with dark values, it will make it sound brighter than it really is.

Many photo editing applications provide as a default background a 50% grey. Lightroom has even the popular “Lights Out” function (shortcut key “L”) that blacks out the workspace. It is supposed to help you view your photo without distraction, but if you use it to judge its brightness, I can bet that you will end up processing your photo too dark. This is especially true if your ultimate goal is a print, but even on a screen, the photo will appear too dark when placed o a white page such as this one. Some websites allow the viewer to change the background color from white to black, and I’ve seen some nature landscape photographers recommend to their readers to use the later for a viewing experience that does justice to their photos!

My recommendation is to process images with the background color set to white. This can be done in Photoshop in Photoshop > Preferences > Interface, and in Lightroom with Lightroom > Preferences > Interface. In Lightroom, to get a generous amount of white space around your photo, in the Navigator window at the top left of the screen, select 1:8.

Think about the fact that if your photo ends up displayed in a gallery or museum, there are great chances are that it will be surrounded by a white mat! And even in more modest settings, are your own walls light or dark colored? With that in mind, it does make sense to use a white application background, doesn’t it?