A Primer on Features & Functionality

At this point, reliability isn’t nearly as much of a gage of quality as it used to be; even the cheap triggers have been through enough design iterations and have fixed most of their early reliability problems. Instead, the biggest differentiating factor between all the radio trigger systems is features that expand the capacity beyond simply triggering a flash or camera.

Addressing Gear: Channels, IDs, and Groups

Any kind of triggering system that doesn’t rely on wires uses some kind of shared medium, and any time there are multiple things on a shared medium there needs to be a way to address those things. This brings me to the most fundamental feature set, the trigger’s addressing system.

Various brands use different terminology and different mechanisms to deal with the addressing. The terms you want to be familiar with are channels/frequencies, IDs, and groups.

• Frequency – The radio frequencies the device transmits and receives.
• Channel – A high level grouping of devices to keep photographers from triggering each other’s cameras or flashes.
• ID – An address that is encoded inside the channel to specify which devices should listen to this signal.
• Group – An address that’s encoded inside the channel to specify specific a device or groups of devices to be triggered.

Not all systems use the same terminology, in some systems channels are more like device IDs, and frequencies are hidden from the user. A lot depends on how the triggering system communiciates between units. The actual technology can become quite complicated, and many systems blur the lines in a lot of places, especially when the system has been around long enough to evolve more features.

Using different radio frequencies, is the simplest way to allow multiple users to work in the same area without triggering each other’s strobes. Systems that are more complex will use digitally encoded packets for the actual control signals. Those packets will often contain ID and group information, which selectively fires flashes without having to give each photographer their own radio frequency.

More frequencies can be useful, but they aren’t strictly necessary. A typical studio shooter will use 1 channel and likely not have to worry about interference form others. On the other hand, the more photographers you get in an area or event, the more frequencies, channels, and IDs you’ll want to have available.

Groups are similar to IDs in a sense, though groups are used for logical organization of flashes or cameras inside a photographers channel or ID. In other words, your channel or ID would identify all of your flashes or cameras, and your groups would selectively identify your key, fill, hair and background lights.

Frequencies

What I’m talking about here is the actual frequency the transmitters work on. Many RF systems these days use the ISM (Industrial, Scientific, Medical) bands, specifically the 2.4GHz spectrum (from 2.400GHz to 2.500GHz). If that range looks familiar, it’s because many things run on these frequencies, from cordless phones, to wireless networks. On top of that, many devices, like microwave ovens, can emit interference on these bands when they’re running.

Other devices, most notably LPA Design’s PocketWizards, run on licensed spectrum that is outside of the typical ISM bands. As a result, in some cases these devices are less susceptible to environmental interference, though they are certainly not immune.

The one downside to running outside of the ISM bands is that there aren’t international treaties that set aside the space. Meaning that in various regions the regulations may require non-ISM devices to operate on different frequencies. LPA Design’s PocketWizzards for example, use 340-354MHz in North and South America, 315.50-317.00 MHz in Japan, and 433.62-434.22MHz in most of the rest of the world. A PocketWizard user who takes their US PocketWizards into Europe and uses them can be found, if caught, in violation of the law and penalized for using radio spectrum they’re not licensed or allowed to use.

Range

The next consideration in remote triggers is range. Aside from simply allowing one to get rid of wires, radio triggers provide users a means to fire cameras and flashes at great distances. How much range one needs varies, and more isn’t necessarily better, just more.

Some of the longest-range units can provide reliable sync signals as far as 1600 feet (500m). Most systems are limited ranges of 300 feet (100m) or 100 feet (30m).

In most cases, 100 feet is often enough range for most wireless flash situations. That said, while it’s not directly summed up in range, longer ranges often have transmitters that are more powerful and better antennas, meaning that they also tend to be more reliable at shorter ranges when in environments that aren’t conducive to radio transmissions. While a system rated for 100 feet may be capable of doing that in an empty field in the middle of nowhere, it may not work reliably across a 30 foot wide room filled with people.

Remote Power Adjustment

The heading is very much self-explanatory; some systems offer a means to remotely adjust the power of the flashes from the controlling camera. Sometimes, this is coupled with TTL metering, other times it’s just manual flash control at a distance.

Remote power control is one feature that can make a shoot go significantly smoother. Moreover, I’d argue that the fewer assistants and more pressed for time you are, the more likely remote power control will be useful. Instead of having to walk over to a flash to make an adjustment, you can make the adjustment on the fly and keep shooting. As a result time can be used more efficiently to squeeze in an extra couple of poses or setups, instead of having to manually adjust you lights.

TTL Metering

The final major feature that’s worth considering is TTL integration. TTL integration allows the camera’s meter to and computer to communicate with the flashes to set flash powers automatically.

The major consideration when it comes to TTL systems is compatibility. For starters, any TTL capable system not implemented by the camera manufacturer itself is reverse engineered. This isn’t necessarily bad, but it does mean that support for new cameras and flashes may take some time.

Advanced Features

There are a lot of other interesting features that some systems add on top of basic flash control. The range and scope of these features can vary considerably.

Some systems offer the ability to save settings to a computer or micro-SD card. Others offer ways to cycle through flash units to provide them more time to cool down and recharge.