Instead of having a grip truck or a large van's worth of big lighting packs, innovative pros like Joe McNally travel with a hard case containing a dozen or more small flash units, compact stands and a case of gels and small modifiers. To make the most of such a system, you need to be able to position and control those flash units in some precarious spots. Line of sight is seldom possible.
The most sophisticated wireless options are radio transmitters. They offer almost unlimited placement options, and they don't rely on line of sight. The transmitter and the receiver often can be placed at a great distance, around corners, behind objects and furniture, etc.
In addition to the placement, radio transmitters give you a lot of control options. Depending upon the specifics of your setup, a radio system can allow you to fine-tune the settings of your individual flash units from the master controller.
RadioPopper PXThe RadioPopper PX transmitter works in conjunction with a flash unit that you've designated as the master unit. The master flash unit emits a set of pulses that, if you were using a simple, optical line-of-sight system, would trigger your slave units. The RadioPopper PX picks up that set of encoded pulses and acts as a radio relay, sending the signal to a receiver unit, which is attached to the slave flash. The receiver translates the radio signal back into the original optical code to fire the slave flash accordingly. It's a simple and reliable system that doesn't require electronic connections between any of your components. It just translates the optical signals to a radio signal and then back to an optical signal. The main benefit of the RadioPopper PX system is that it frees your various devices from the needs of line of sight without adding a lot of complexity or complications. The RadioPopper PX has a range of approximately 1,500 feet, it's Canon- and Nikon-compatible, and it supports high-speed sync up to 1/8000 sec.
PocketWizard MultiMaxFor a lot of pros, PocketWizard has been synonymous with wireless capability like Xerox has been synonymous with copier machines. The MultiMax is the company's most advanced model, and wireless flash triggering is only one part of its feature set. The MultiMax's Quad triggering gives you four individual equipment zones with cameras and/or flashes that you can trigger. That lets you remotely control both cameras and flash units from a central location. Sports photography is an obvious use for this kind of feature, but creative shooters are finding plenty of other benefits. For example, having multiple cameras fire simultaneously to give you a variety of different perspectives on a shot can be particularly helpful when you're working with a shot like breaking glass or splashing liquid. The MultiMax has an effective range of about 1,600 feet, and it's a true radio system that connects to your devices electronically. It can act as an intervalometer controller for time-lapse, you can use multiple units to relay signals if your needs exceed the 1,600-foot range, and it can seek out the best frequency to use. If you need multi-pop control, the MultiMax can trigger a flash unit to fire 10,000 times on a single exposure. It's hard to imagine needing that, but more mundane multi-pop usages abound.
Elinchrom EL Skyport WiFiThe Elinchrom EL Skyport WiFi gives you triggering control from Apple iOS devices, essentially turning your iPhone or iPad into a wireless remote triggering device. Using the EL Skyport WiFi with Elinchrom RX flash units gives you a full range of control over those units, and the EL Skyport WiFi also can serve as a Universal Speed Receiver, giving you connectivity to most other flash systems. It has a range of about 150 feet outdoors in WiFi mode and about 60 feet indoors in WiFi mode.