Photographing fireflies requires a camera that allows full manual control, a fast lens, a sturdy tripod, and a plan to arrive before dark. The technique combines long exposures in near-total darkness with image stacking in post-processing to produce those iconic shots filled with hundreds of glowing trails. Here’s how to do it from start to finish.
Gear You Need
A camera with manual mode and a lens with the widest possible aperture are the two essentials. Fast prime lenses (those with a maximum aperture of f/1.4 or f/1.8) outperform zoom lenses in this situation because they gather far more light. A 35mm, 50mm, or 85mm prime works well when you want soft, blurred backgrounds that make the firefly trails pop. A wide-angle lens is better when you want to capture an entire landscape filled with flashes.
Beyond the camera and lens, bring a solid tripod, an intervalometer (external or built into your camera), extra batteries, and a red headlamp for navigating in the dark. If you’re shooting in a humid area, a USB-powered lens heater strap prevents dew from forming on your front element. These wrap around the lens barrel and plug into a portable power bank. A cheaper alternative: activate two or three chemical hand warmers and rubber-band them around the lens near the front glass.
Camera Settings to Start With
Set your aperture as wide as your lens allows. If you have an f/1.4 lens, start there. Set your ISO to 1600 and your shutter speed to 30 seconds. This combination is a reliable starting point that you can adjust based on conditions. If the background comes out too bright (from moonlight or nearby light pollution), shorten the shutter speed rather than closing down the aperture. You want to keep the aperture wide to capture the faint glow of each flash.
Earlier in the evening, when some ambient light remains, you may need shorter exposures in the range of 4 to 8 seconds. As full darkness sets in, stretch your shutter speed longer. In very dark locations with no moon, exposures of 20 to 30 seconds or more work well. The goal is to slightly underexpose the background so the firefly trails stand out against a moody, dark scene rather than a washed-out one.
Focusing in the Dark
This is the step that trips people up most. Autofocus is essentially useless in near-total darkness, so you need to set focus manually before losing the light. Arrive at your location while there’s still enough daylight to compose your shot and lock focus on a tree, a path, or whatever element anchors your scene. Once you’ve nailed focus, switch your lens to manual focus mode so it doesn’t hunt when you start shooting.
Mark the focus ring’s position with a small piece of tape on the lens barrel. If you accidentally bump the ring in the dark, you can feel your way back to the correct spot without turning on a light. Cover any autofocus-assist lights on your camera body with tape as well, since a sudden red or green beam will disturb both the fireflies and other photographers nearby.
Starting your shoot while some light remains has another benefit: those early frames show you how the surrounding foliage, tree trunks, and ground look at various exposure levels. They become reference points when you’re editing later and trying to decide how bright to make the final background.
Shooting a Sequence for Stacking
A single 30-second exposure will only capture a handful of firefly trails. The images you’ve seen with hundreds of glowing streaks are composites, built by stacking dozens or even hundreds of individual frames. An intervalometer automates this process. Set it to fire one shot after another with a one-second gap between frames so the camera has time to write to the card. Program it to take 100 to 300 shots, then let it run for an hour or two while you sit back.
If your camera has a built-in interval timer (many newer models do), you can set this through the shooting menu without any extra hardware. Choose your interval time, set the number of images, and start the sequence. The key is consistency: don’t touch the camera or change settings mid-sequence, because every frame needs to match for stacking to work cleanly.
Stacking Your Images
Back at your computer, you’ll combine the entire sequence into one image using a “lighten” blending mode. This keeps only the brightest pixels from each frame, so every firefly flash from every exposure appears in the final result while the dark background stays unchanged.
Free software like StarStaX handles this efficiently. Import your full sequence of images, select the “Lighten” blending mode, and let it process. The output is a single image with all the firefly trails layered together. If you shot in raw format, convert your files to TIFF first using your preferred raw editor (Lightroom, Capture One, or similar), making sure you apply identical adjustments to every frame before exporting. Photoshop can do the same thing: load files into layers, then set every layer’s blend mode to “Lighten” and flatten.
A practical workflow looks like this: pick the single frame with the best-looking background, edit it carefully for color and exposure, then sync those exact settings to all remaining frames. Export them all, stack in StarStaX or Photoshop, and do final adjustments on the composite.
When and Where to Shoot
In the eastern United States, firefly season generally runs from late May through July, depending on latitude and species. One of the most famous displays happens at Elkmont in Great Smoky Mountains National Park, where synchronous fireflies flash in unison during late May or early June. The park limits access during an eight-day window of predicted peak activity (May 29 through June 5 in 2025) and requires a vehicle reservation obtained through a lottery.
You don’t need a national park for good firefly photos, though. Any area with tall grass, wooded edges, and low light pollution during the right season can produce strong displays. Fireflies prefer warm, humid, still evenings. Peak flashing typically starts 30 to 45 minutes after sunset and lasts one to two hours, though this varies by species. Scout locations during the day so you can identify compositions, find flat ground for your tripod, and note any sources of artificial light that might wash out your shots.
Protecting the Fireflies
Every light source you bring into a firefly habitat suppresses their courtship. Research from Tufts University found that all colors of artificial light significantly reduced courtship activity, but amber light had the greatest impact on female receptivity. That’s particularly notable because amber lights are often promoted as “wildlife-friendly” for other species. For fireflies, no color of light is safe. They need darkness.
This means you should avoid using white flashlights, phone screens, or camera LCD screens at full brightness in the shooting area. Use a dim red headlamp only when necessary, and shield it with your hand. Turn off your camera’s rear LCD review or set it to its dimmest level. Never use flash. If you’re with a group, agree on a lights-out policy before the show starts. The fireflies you’re there to photograph are actively trying to find mates, and every stray photon makes that harder.
Stay on established trails or paths to avoid crushing firefly larvae in the leaf litter, and resist the urge to catch fireflies in jars for close-up shots. The best images come from patience and preparation, not from handling the insects.