The first distinction of the two systems is the way in which they trigger flash. The optical system relies on a line-of-sight connection between flash units. That is, for a unit to fire, it needs to be able to “see” another flash from the system. Some cameras allow the use of a built-in pop-up flash or another flash in the system to act as a master unit that doesn’t affect the exposure, but simply transmits a light pulse that triggers the slave units. There are a number of options for configuring an optical system, but you can’t get around the line-of-sight issue. The benefit of this optical configuration is that it’s relatively low cost and often easy to set up, but its limitations are in the line-of-sight restrictions and the occasional unpredictability of the system. The flash slave systems must be in the optical path of the master to be triggered, and the range at which you can move around is usually restricted to 40 feet or less.
On the other hand, we have radio-controlled transmitters/receivers to trigger strobes. The transmitter is connected to your D-SLR’s hot-shoe, while the receivers are connected to a power pack. With this setup, you can transmit a radio signal to your flash and quickly fire off shots with very consistent results and output. The radio triggers vary in their operational distance—anywhere from 100 to 1,600 feet—depending on the transmitter. The key benefits of a radio-controlled system are the increased range and the security of your strobe network. If you’re shooting a sports event, for example, you can position radio-controlled units all around and set them up so that no one else’s cameras will fire your network. One of the limitations of using a wireless radio transmitter is that many cameras’ TTL metering won’t work, and these units also tend to be somewhat more expensive than an optical system.
Most camera manufacturers have high-end flash units, and most of them can be used on master mode for slave unit shooting. Canon uses the E-TTL II system in which its Speedlites can be triggered by setting the camera to master so that the flash units can be simultaneously triggered. On the high end, the Canon Speedlite 580EX II and the new Speedlite 430EX II both can be remotely triggered, and the flash units are capable of automatically setting their own exposure through the lens.
Nikon’s Creative Lighting System sets its Speedlights to a commander mode as the master unit. For the D3, it uses an i-TTL-compatible hot-shoe, or if you’re shooting with a D300 or D700, you can trigger the Speedlights with the camera’s built-in flash as the commander. The Creative Lighting System consists of various Speedlights. The new SB-900 is a particularly noteworthy unit because it lets you control up to three remote Speedlight groups and an unlimited number of compatible Speedlights in its range. The Olympus E-3 can be set with its pop-up flash in a commander mode to control a group of external flash units. The E-3 can trigger up to three different flash groups, including the new Olympus FL-50R and older Olympus flash units like the FL-36R. The optical RC Data Transfer System triggers surrounding flash units and lets you set or turn off different sets of lights through the RC mode in the E-3. Its features also allow the camera’s TTL auto, manual and auto modes to be fully utilized.
The Sony HVL-F58AM flash unit incorporates Wireless Ratio Control to control up to three groups of flashes and specify the luminosity ratio for each of the three groups, providing multiple-flash lighting schemes. Also of note, the Sigma Electronic Flash EF-530 DG SUPER has a Designated Slave function, which lets you use two or more EF-530 DG SUPER flash units.
The main advantage to radio triggers is the range at which you can move wirelessly and trigger groups of strobes and flashes. The PocketWizard MultiMAX Transceiver can be triggered from 1,600 feet between transceivers. While you may not need that kind of range, it shows the capability of radio signals. Other benefits of the MultiMAX are multi-channel switching for controlling different lights, a sustained 12 fps high-speed-triggering ability and Selective Quad Triggering that lets you control firing sequences of various strobes no matter the brand.
works with Elinchrom units, as well as other flashes and power packs. It includes a transmitter that you connect to the camera’s hot-shoe and a transceiver to connect to the flash unit. The EL-Skyport system has a range of 164 feet, and it allows you to adjust and sync individual units or groups of flashes and strobes.
MicroSync Digital is a very compact system that uses radio signals to synchronize groups of flash units or power packs. Link the transmitter to your camera’s hot-shoe and the receiver to your power packs up to a distance of 100 feet.
The Elinchrom EL-Skyport Universal Radio Slave Set is a wireless radio slave system that Quantum’s FreeXWire System utilizes eight different radio channels and gives you four zones of control, allowing you to selectively control four different sets of lights. Another great feature for Quantum Qflash 5D users—you can get wireless TTL control with the system. The FreeXWire transmits your camera’s ƒ-stop, ISO and TTL exposure information to the Quantum flash to make adjustments. The FreeXWire has an impressive range of up to 1,000 feet.
Elinchrom (Bogen Imaging)