Symphony of Light–Synchronous Fireflies @ Smokies

Canon 7D : Canon 10-22 mm : ISO 400 – 3200 : 10 mm : f8.0 : 30 sec ; 245 Shots

Gatlinburg, Tennessee, USA


The Fireflies

For two weeks, each year, during the endless nights, the secluded forests of Elkmont is converted into a magical wonderland.

Photinus carolinus – or more commonly known as Synchronous fireflies – puts an amazing show each year around May – Jun, at the lovely mountains of Smokies. Unlike other fireflies, this species uses the synchronicity of the flashing, probably to attract it’s mate. No one is sure why the fireflies flash synchronously. Competition between males might be one reason: they all want to be the first to flash. Or perhaps they flash together, so they have a better chance of being noticed.

Fireflies – showcases a prime example of bioluminescence – combining the chemical luciferin and oxygen with the enzyme luciferase in their lanterns (part of their abdomens) to make light. The light produced is referred to as a “cold” light, with nearly 100% of the energy given off as light. In contrast, the energy produced by an incandescent light bulb is approximately 10% light and 90% heat. So much for our human invention :)

Synchronous species of fireflies are very special—and they exist only in a handful of places throughout the world. Elkmont @ Smokies is one such place. These fireflies flash their little green-yellow bioluminescent lanterns in unison for about 6-8 blinks and then they go dark for a few seconds creating a sublime wave of light throughout the forest.

If you are interested with how this was shot & processed, continue reading … else here are few more shots for you to enjoy.


Behind the Scene

To watch the fireflies, it was quiet magical. To get them in a frame, it was quiet elusive !

The key to getting this shot was being at the right place, at the right time and a bit of luck. Once, these fell in place, it was time to wait. Not long after, the horizon begin to darken and the first of the fireflies being to twinkle. Here a twinkle, there a twinkle and before you know it – everywhere a twinkle. The entire night lit up in it’s mythical glow.


In the recent years there had been a significant decrease in fireflies. This could be attributed to various climate changes, human footprint, light pollution etc. On top, the species of synchronous fireflies are even more rare in occurrence. There are only very few places that hosts these lovely angels – Smoky Mountains, Congaree National forest,  Allegheny National Forest, South Asian Mangrove Forest and Oak Ridge Wildlife Management Area.

Although it takes the lightning bugs one to two years to mature from larvae into adults, the lifespan of an adult is extremely short. Adult fireflies only live two to three weeks and don’t eat any more meals once they are an adult. The synchronous flashing happens as part of it mating ritual, for about week to two annually. In the US this is around May to June and depends on  temperature, humidity, moon light etc.


One of the most popular places to view the Synchronous Fireflies in the Great Smoky Mountains National Park is around Elkmont. The reason for popularity could be because, the National Park scientists use air and soil temperatures to predict the timing of each year’s mating season and publish the same via NPS website. This event has become so prominent, that a lottery system was instituted from 2016 to gain entry. During this time, access to Elkmont is closed at night time, with the exception of approved lottery users.

Last year, I was not lucky enough with the lottery. But that helped to identify a new option to gain entry. This is my preferred option too. Though I did get the lottery this year, I still went with the latter. Not may folks are aware – but if you manage to secure a camp site reservation, you would have access to the campground and the trails. A huge advantage to this option – you would have access to all trails and not just be restricted to the public viewing area (initial 3/4 Mile of the Little River trail & Johns Creek). This greatly helps get to secluded spots, that are not hindered with flash lights and mobiles from passersby. But a word of caution, Elkmont campground is quiet popular and fills up months ahead. It takes some persistence and luck to grab a spot when a cancellation comes up.

Ideal conditions would be an overcast sky or around a no moon night, so the moon light is not competing with these little fellows. This year though it was neither cloudy nor anyway close to a no moon day. This resulted in subdued and delayed firefly activity. This also made scouting for the location more critical. It was much easier to walk around when there was still twilight , to hunt for canopy of trees that would block the moon light. Once I got a decent spot and a composition I liked, it was a matter of setting up the camera and wait !

Set Up for the Shot

Shooting fireflies is very similar to shooting the stars. I personally prefer shooting multiple small exposure as opposed to one long exposure. This gives lot of creative freedom with Post Processing.

One of the crucial factor for this was to get the background exposed right. It is good to get the yellow specks of the flies, but getting them right along with the environment was more intriguing. This meant being on the location before the darkness begin to engulf the scene. The twilight also helped with getting to know the surrounding, so there was not flash light needed later :)

Focus : If you have one the recent Sony cameras (A7SII, A7RII, A9) with crazy ISO, that can literally see and focus in the dark, you are good. Else it is better to focus as needed when there is ambient light and change to Manual Mode. Setting to infinity might not really help as the foreground is generally much closer. It even helps to lock the lens with a Gaffers tape, once the focus is set. This would ensure the focus is where we want thru the last shot !

Tripod & Remote Trigger: Since it would be a sequence of shots over a period of time, having a tripod is crucial. A sturdy tripod in conjunction with remote trigger would be ideal. A remote trigger with continuous shooting or intervalometer option would enable shooting continuously with out physically initiating each click.

Base Shot : Depending on the ambient light , get several of exposures of the environment. This ideally would be in low ISO. The best of your base shot could be got from just before it goes dark. Shooting with a cool white balance would go with this. At this time, feel free to increase the exposure time with lowest ISO for minimal noise.

FireFlies Shot : For this you want to get as much as possible. So shooting with a larger aperture is preferred. Anything less than f2.8 would also reduce the depth of field. Hence getting the getting the required focus in the beginning is critical. The aperture also would greatly define the feel of the shot. A wide aperture like 1.8 would throw the near by fireflies out of focus, given a smooth bokeh feel.

The shutter speed would depend on the brightness of the flash and the effect you are targeting for.

You would want to shoot with a higher ISO for getting the fireflies. On a Canon 7D I had gone up to 6400 and still got workable images. The noise generally is in the shadows / dark areas and can easily be addressed via post processing. The higher the ISO, the fainter and distant fireflies are captured :)

You can try out different options and see what works for the night. In this case IS 3200, F3.5 and 30 sec exposure worked pretty well (If the moon had not been there and the activity was higher, I would have reduced shutter speed down to 15 seconds).

Post Processing


2 hrs 55 mins of continuous shooting
245 Frames
250 layers
Merged to a single frame
6.84 GB PSB file
Should be an interesting result :)

Shooting from 8:45 thru 11:40 PM, ended with 245 frames.  At a high level the processing is simple – Have the base layer with Blend Mode of “Normal” and all the fireflies layer with the Blend Mode of “Lighten”. Since I had around 245 frames setting the blend mode one layer at a time would have been tedious. My Star Trail Scripts comes in handy for this by setting the blend mode in a single click (refer this article for details).

In case there are any unwanted light streaks from passers by, it would show up in the final shot. The advantage of using smaller multiple exposure is that you could delete that particular layer or just mask the distracting portion of the layer. Skim thru each layer masking out unwanted portions, if any.

Once you are happy with the final effect, duplicate the base layer and merge all but the new duplicated base layer. You would end up with a layer with Background and one more layer with Background including the fireflies.

Changing the Blend Mode to “Duplicate”, would help create a layer with just fireflies.

Base Layer – (Base Layer + All FireFiles Layer) = Fireflies only Layer

– Blend mode of Difference
+ Merged Layers
= Merge All to save a new layer

Having these separated would aid with the any additional processing as you creatively feel fit :)

Dying daylight & rising twilight,
Kindles the tiny angels of the endless night.
It is quiet a sight
Witnessing the symphony of light.

Specks of light, Shining bright,
Weaving a silent song by moon’s light,
So nimble & ever in flight –
To watch them twinkle, is always a delight :)


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