Capturing fireflies’ light tracks in camera is something modern high-sensitivity digital cameras can do very well. Micro Four Thirds systems have a nice trick to do long exposures even better and I was lucky I got an Olympus Pen F just in time for this year’s display.
It is not hard to arrive at the settings for showing the fireflies’ light traces, while keeping enough detail in the ground, if you shoot when there is a bit of light in the sky. Luckily, twilight is precisely the time when the little beetles are the most active. In my case, 2 s at f/2.8 and ISO 1600 did the trick.
During a single 2s exposure you get some tracks but nothing too impressive. What you would like is a longer exposure to get many tracks but the problem is that light keeps adding up in the foreground and, after a while, it no longer looks like a night photo. If you make instead several shorter exposures with the right settings there is a way to combine the light tracks from all your shots while keeping the background dark.
The way to combine the exposures is to load all your well-aligned, tripod-made exposures in successive layers in Photoshop and set layer blending mode to Lighten. The software then just shows the brighter pixels added to the bottom (base) exposure and you get all the flashes you captured together.
Olympus cameras can do this automatically in camera, and you even get to actually see in the camera’s display how each image is added in real time. Awesome! This allows you to keep adding images with light tracks until you are happy with the result. Panasonic cameras do something similar too using their 4K mode.
The technique can be used to photograph fireworks or car headlights on a highway, for light-painting and other night photography techniques, with the advantage of having control over background lighting and seeing your image coming together as you shoot.
One thing I noticed is that fireflies’ light flahes have very different duration in the places I have visited. Very short near my home and much longer in the highlands.
How long are their flashes in your location, sort or long? Have you tried to photograph them? I am very interested to know more about the lightning bugs!