Flash Mob

by Lisa Mulcahy

Paule Constable’s lighting design for War Horse used Martin Atomic 3000 DMX strobes during the battle scenes.
Paule Constable’s lighting design for War Horse used Martin Atomic 3000 DMX strobes during the battle scenes.
Create smashing strobe lighting SFX safely—even with a big cast and capacity house

Strobe light and flashing SFX can be a real visual boon to a production, or a real pain in the neck. The more people involved in these effects—cast, crew or audience—the more things can go wrong. Crew members and actors have to be well-rehearsed to move properly under the disorienting effects of strobing, and some audience members can actually suffer medical problems (such as seizures) when viewing strobes. Still, strobe lighting can be an incredibly versatile tool, and a great way to add pop to your show.

Strobe Basics

Strobes come in a number of prices ranges and wattage, from the traditional halogen or xenon lamp to the recent arrival of LED sources. Your basic strobe is a plug-in device like the American DJ Big Shot, a 45-watt light with a halogen source. There are more complex, multiple source fixtures like the MegaStrobe FX12 from Chauvet Lighting, which contains multiple LEDs, is controllable via DMX and can be used as a singular strobe light or programmed to have chase effects in the fixture. On top of the power scale you have instruments like the Martin Atomic 3000 DMX, which uses a 3000 watt xenon lamp to blast your viewers; Paule Constable used eight of them for her lighting design for War Horse on Broadway.

No matter the size, strobes tend to pack a powerful punch, so you’ve got to carefully plan them into a production. A few short, dramatic flash bursts lensed in white can perfectly mimic vivid lightning; you can also create unique stage pictures with colored strobes; and you can also use a strobe to light a slow-mo visual tableau. Just don’t do them all.


Kevin Richie
Kevin Richie

“When using strobe or flashing effects, I think it is important to remember that there are people watching your show, and that, while strobes lend themselves to great effects, using them too often or for too long leads to the audience becoming annoyed by them,” says Kevin Richie, president and co-owner of StageSpot.com, a retail production supply company based in Austin, Texas and a veteran Broadway and regional lighting tech.


Additionally, where you place a strobe can have a tremendous impact on how well the effect will read from the stage. A strobe flash that originates too close to another source of stage light is most likely going to get swallowed up and washed out, either partially or completely. Placing a strobe upstage, away from clashing light sources, will maximize its impact. It’s also not a bad idea to take the intensity of the rest of the rig down a few points around the timing of a strobe to avoid washing the effect out.

Keep in mind, too, that the closer an audience member is to a strobe, the more vivid (and potentially, visually assaultive) its result will be. Don’t overwhelm the audience! “More typically, strobe lends to a better effect when the flash can be contained on stage,” adds Richie.

Health and Safety


Noemi Ybarra, lighting specialist at Jones & Phllips Associates
Noemi Ybarra, lighting specialist at Jones & Phllips Associates

Unfortunately, another effect strobe lights can have on your audience, as well as your cast, crew and staff, is creating potential health hazards. “We know that strobes can trigger seizures,” stresses Noemi Ybarra, lighting specialist at Jones & Phllips Associates, a theatre consulting firm in Lafayette, Ind. Audience members with photosensitive epilepsy, specifically, can suffer seizure episodes by looking even briefly at a strobe SFX.


The number of strobe flashes you program per second can influence a susceptible audience member’s seizure risk. It’s believed that an effect containing eight or more flashes is most likely to cause a medical issue. Many theatre safety experts, therefore, caution clients never to operate a strobe at more than five flashes per second. Don’t put any patron at potential risk: Consult a doctor, and ask this physician not only to inform you accurately of seizure risk in accordance with your production, but to come to your rehearsals and personally view your strobe SFX to confirm its safety.

It’s also imperative that you contact your city or town’s local government to ask if there are any state or local licensing or safety inspection requirements to fulfill prior to operating a strobe effect. Taking the initiative and actually asking to have a health or safety inspector sent out to you is a great idea, to make sure you are absolutely playing it safe.

And don’t forget your crew, staff and performers. In a large working group, one or more members of your company could suffer from epilepsy and potentially not even know they have it until exposed to a trigger, such as a strobe.

“Van Phillips, our company’s principal, and a veteran lighting designer himself, cut strobe lights from a production because they affected an actor who was prone to seizures,” remarks Ybarra. Don’t hesitate to sacrifice an effect if it puts someone’s health in jeopardy.

Also, never point a strobe directly at any patron, actor or crew member—if that’s your vision, scrub that blocking pronto.

Strobes can also cause injury to your company’s member by inhibiting their movement. “Actors are often required to move onstage while lights are flashing, making it difficult for them to see,” notes Ybarra. “Plenty of practice is essential, as well as good safety warning lights at stage edges. No falling into the pit!” To ensure this, keep everyone on the same page.

“When working around a stage with strobe or flash effects, specifically during a rig check or other ‘tech’ time, remember there are others working around the stage who are completely unaware of what you are doing,” says Richie. “Audio people are checking their rig, as are the carpenters. Before you starting flooding the stage with flashes, call a warning, make sure no one is looking directly into a strobe before you fire it off. The last decade or so has seen the advent of some very powerful strobes, it may not always be necessary to check them using full power.”

Above all, think and plan ahead. “I’m not sure if there really is any way to get people used to strobes, but definitely getting them accustomed to when the strobes are used is a possibility,” says Richie. “If you are working on a production with a large amount of flash effects, I would be sure to discuss their placement and use during a company meeting. Otherwise some shouts from the tech table before the one scene in which they are to be used should be sufficient to let folks know the strobes are coming. Obviously you can’t do this during a show, but in rehearsals, it will get people to start expecting them during the show.” Include your strobe SFX in at least five rehearsals outside of traditional wet tech, so your actors and crew can all get used to working through them.

Getting the Word Out

Once you’ve safety-proofed your operation and familiarized your actors with your strobe SFX, it’s time to alert patrons to their role in your production. “The typical placards in the lobby, stuffings in the program and announcement before the show are great to let audience members know strobes will be utilized, but really don’t help for people who don’t know the show,” Richie advises.

“Again, I would be careful not to over-use the effect and to not point any strobes directly at the audience,” Richie continues. “If it’s easy enough and wouldn’t hurt the integrity of the show, a mention in the placards or announcement that strobes will be used at the end of the act or throughout may be helpful.”

“Early warning is the best way to go,” concurs Ybarra. “In addition to warning signs outside entrances to the theatre, that same information should be included on advertising and at the box office.”

As in every part of running your theatre company, honesty, transparency and respect for your audiences is key when it comes to executing strobe SFX for large groups—or groups of any size. As Ybarra wisely sums up: “Not only don’t you want audience affected during the performance, you don’t want them to buy a ticket only to arrive at the theatre and be disappointed that they can’t attend the show. No surprises!”