We live in a new Golden Age of photography. The new digital cameras have an uncanny knack for seeing in the dark. How else could I have gotten this picture of the fireflies for our story on the Flint Hills of Kansas?
The bare facts are these: 76 second exposure at f2.8, ISO 1600. Problem is, the bare facts don’t usually tell you what you need to know.
So let me go a bit deeper into what brought this picture about. There are several key factors if you are going to photography fireflies. The first is the fireflies (naturally.) If you are an entomologist you won’t be surprised if I tell you there are a whole lot of firefly species. You’ll probably say, well, no duh! And there are a corresponding range of mating behavior and flashing patterns. If you are a firefly bent on mating tonight you kind of need to find one of your own species. And you want to avoid the various cannibalistic species that will home in on your flashing tailpipe and have you for dinner. (I’m not kidding.)
So you’ll likely want to go to one of the firefly singles clubs where thousands of fireflies gather to, well, do their firefly thing. And if you are a photographer you want to be on the lookout for one of these swarms. Light level is critical to the fireflies, also, so be aware of when the light of dusk gets low enough for them to “turn on.” This is why you’ll see them beneath trees where the shade is darker in the early evening.
I also had a very calm night on this evening with a storm approaching from the west. The field was awash in blooming wild alfalfa, the blue of the flowers augmented by the deep blue light a good 45 minutes after sundown. And it was dark. So dark I couldn’t see though the viewfinder. I simply had to guess at where the lens’ focusing ring should be and take a test exposure. When that one showed I was too dark and too close I adjusted to a longer exposure and reset the focusing ring a little bit.
And now we come to the other trick. I was shooting with a telephoto, in this case a 70-200mm zoom set out towards the long end. This is important. You need the stacking effect of the telephoto to get more fireflies into the picture. Go out on any night with a pair of binoculars and you’ll get the same effect. You’ll simply see lots more fireflies.
Note too that the 76 second exposure meant that some fireflies showed up several times, like that big one going right across the picture in regular flashes.
When I shot this two years ago I was right out on the edge of what the cameras could do. The Canon 5D that I used at the time was then the best out there, producing quite usable results at ISO 1600. Today my Nikon D3 can produce comparable results at ISO 4000-6400. (And I suspect the new Canon 5D will pretty much do the same thing, when it becomes available, like next week.)
And if I could do it over again with a 200mm f2 lens I’d be that much better off. But then I would have to find that perfect swarm on just the right night with just the right field of wild alfalfa. Maybe I’ll get lucky. After all, as I said in the beginning, this is a Golden Age of photography.