It’s safe to say that LEDs have revolutionized continuous lighting by delivering smaller, cooler, more energy efficient lights to market in a truly impressive variety of shapes and sizes.
Yet for all their virtues as a continuous light, LED technology hasn’t made nearly the same inroads in flash photography. But some manufacturers, such as Rotolight and Lume Cube, have brought LED flashes to market that offer a tantalizing glimpse of what the technology can deliver for still photographers.
We spoke with manufacturers and photographers to get a sense of the pros and cons of using an LED flash for photography.
Zero Recycle Time
Your traditional flash is fired using a capacitor, which must recharge itself before firing again. This recycle time can be very brief, mere fractions of a second, but it still introduces a lag between when the flash fires and when it’s ready to fire again, especially as you increase the power of your flash. “In that 2 to 3 seconds, you can miss the moment,” says Rotolight managing director and co-founder Rod Aaron Gammons.
LEDs don’t require capacitors, so there’s no recycle time, even at full power. “I’ve shot my camera at 12 fps in sync with the flash with zero recycle time,” says wedding and portrait photographer Brett Florens, who uses Rotolight’s NEO 2 and Anova lights. Such speed has helped Florens freeze motion during environmental portrait shoots at gyms, where both camera and flash must keep pace with fast-moving subjects.
“In conventional strobes, you can’t have full power and fast flash duration,” Gammon says. But Rotolight has decoupled those two, allowing photographers to choose whatever power setting they want with no penalty in terms of sync time.
One of the biggest liabilities of an LED flash is that they don’t deliver all that much power. For instance, you can’t use an LED strobe to overpower the sun. It’s tough to compare Xenon vs. LED flash output because the two technologies are measured differently (Xenon in Watt seconds and LED in lux), but Rotolight says its NEO 2 strobe and continuous light offers about the equivalent of a 150 W/s speed light. That’s great for many applications, and with the built-in Elinchrom triggering system, it’s not hard to group multiple NEOs together, but it’s still a lot less power than you’d get in a comparably sized, conventional flash.
One workaround for photographers using LED flash is to lean on the improved ISO sensitivities of their cameras. It won’t help with the sun, but it can help compensate for the lower light output of LEDs. “I have a 45.7-megapixel camera that shoots at up to 25,600 ISO with a very acceptable amount of image noise at such a high ISO,” says Los Angeles-based fine-art photographer Vincent Versace. “So, I can shoot at 2,000 ISO and the LED’s lower light output isn’t a drawback for me.”
What You See is What You Get
Strobe modeling lights are much less powerful than the flashes they’re attached to. They’re also usually off axis from the light, which means they’re not hitting your subject from the exact same direction as the strobe itself. Both of these elements combine to deliver a modeling light preview that’s not precisely accurate.
That’s not the case with LEDs. In the case of the Rotolight NEO 2, there’s only one stop more output in strobe mode than continuous, and the light all emanates from the same place so your previews are spot-on. “With the rise of mirrorless cameras and real-time exposure previews, there’s a natural synergy with using LED flash,” Gammons says.
Versace, who often shoots with one or more Lume Cubes, says there’s another benefit to LEDs: keeping them turned on ensures your subject’s pupils stay contracted. “If I use a strobe in a dark room, people’s eyes are dilated, so you lose sight of the eye itself when you shoot,” Versace says.
No TTL Metering
Through-the-lens metering enables your camera to tell your flash how powerful it needs to be for a proper exposure. LED strobes, as of now, don’t support TTL and have to be operated manually. You, not your camera, must tell the LED how powerful it needs to be. “Understanding how flash works is important,” if you’re going to use an LED flash without TTL, Florens observes.
It’s a Genuine Hybrid
LED flashes aren’t single-purpose units. They can be used as video lights as well. Florens likes to use several Rotolights on continuous for the first dance: one as a backlight for the bride and groom, and a second that he holds off camera as fill light. “Then, when shooting guests dancing, I shoot the Rotolights as a flash because on the dance floor, it’s irritating to shine a continuous light on [the guests] at all times,” he says.
Dial in Your White Balance
One of the traditional challenges of shooting flash indoors is balancing warmer ambient light, which is typically done with gels. LEDs, on the other hand, offer adjustable color temperature. In the Rotolight implementation, you can dial in the color temperature very precisely without needing gels. This helps you get it “perfect in camera,” Florens says.
Not Many Manufacturers in the Game
Unlike the world of conventional strobe lighting, where there are numerous vendors with products of all price points, there are very few LED makers offering strobe products outside of Lume Cube (which Versace uses) and Rotolight, and a few others. That means you’ll be locked into a manufacturer’s line of modifiers, at least for now. Versace thinks that is going to change very rapidly, though. “This is the future of light.”
Why Have LED Flashes Been So Hard to Build?
An LED flash is a “unicorn we’ve all been chasing,” says Eric Eggly, chief product officer at FJ Westcott. There are two big challenges in developing an LED flash, he says. The first is developing LEDs that can withstand a surge of excessive power.
Conventional Xenon flash tubes produce light in a bell curve, with a ramp up and fall off in light intensity. LEDs, by contrast, deliver all their power at once—as Rotolight’s Gammons puts it, their flash curve is a vertical line. This blast of energy into the phosphors that comprise an LED can wear them down rapidly, a process known as electrical overstress. Photographers expect LEDs to be highly efficient and last for years, but pulsing power into them can result in a dramatically shorter life span, Eggly says.
The second issue has been balancing size with power. Building an LED with the capabilities of a 400 W/s or stronger flash is impractical with today’s technology. Eggly says that to deliver the equivalent power of a Profoto B1 in an LED flash would mean a product that would measure beyond practical or acceptable size standards.
Still, Eggly sums up, there’s plenty of research being done to overcome these challenges, and the technology is moving quickly.