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[] MASTER YOUR DSLR: RADIO-CONTROLLED FLASHWireless radio flash requires two units: a
master and a slave. Only one master unit is
required to control a bank of slaves; it can be
in the form of either a flashgun with master
capabilities or a transmitter unit. Some SLRs
can use their pop-up flash as the master unit
in an optically triggered wireless system.
The advantage of using a flashgun is that
you’ll always be able to add a splash of extra
light if you need it. The master flashgun
doesn’t have to be fixed to the hotshoe
either — you can use an off-camera shoe
cord to position it in a more suitable position
to light the subject, while still retaining its
master unit operation. If you don’t need its
light, you can set the flashgun to transmit
the radio signal only.
A wireless radio transmitter offers the
same level of control and most of the
features, but without additional light. It
attaches to the camera’s hotshoe and it’s
lighter than a flashgun.
Here, you can compare the controls on
the Canon 600EX II-RT and the ST-E3-RT
Speedlite Transmitter...LINK UP
Linking the master and slave units is a
simple case of tapping this button until
the link lamp lights green.AUTOFOCUS HELP
Another advantage of using a flashgun as
the master unit is that it can output an
autofocus assist beam when shooting
in low light. Not all transmitters
(including this model) do this.DISPL AYS
The small screens pack a lot
of information in. Here, the
flashgun indicates it’s in
optical slave mode (note the
lightning bolt icon), while the
transmitter is in radio master
mode (indicated by the
antenna icon).FLASHGUNS VS TRANSMITTERS
When you’re choosing a master unit, should you go for a second flashgun or a dedicated trigger?a slave unit. As a
result, a slave needs to
‘see’ the light from the
master or it won’t fire.
Radio flash doesn’t
have this shortcoming,
which gives you the
freedom to place the
slave units where you
like, as long as they are within operating range
of the master unit. It’s for this reason that
radio flash has rapidly grown in popularity
in recent years. Radio flash isn’t a new
technology, but what was once an expensive,
exotic way to trigger a remote flashgun or
studio light is now mass-market stuff.
In the early days of radio triggering, it was
PocketWizard that was the dominant force.
Now, not only have camera and lightingmanufacturers
developed their own
sophisticated systems,
but there’s a wide
range of affordable
third-party options to
choose from too, such
as those from Phottix,
Cactus and Yongnuo.
You can use radio-controlled wireless
flashes over a greater distance than optically
controlled wireless flashes, particularly
outdoors. For example, in radio wireless
transmission mode, a Canon 600EX-RT
Speedlite has a maximum working distance
of 30m outside, dropping to 15m or less in
optical wireless transmission mode. Some
third-party radio options go much further:
the PocketWizard Plus III which works up to500m in ideal conditions. While you may be
restricted to using fewer slave units in a
radio-based set-up, you can typically arrange
these in a greater number of groups or zones.
A group can contain a single flashgun or
multiple units, and is identified by a letter.
You can control each group independently,
increasing the ratio of power between the
groups so that some produce a greater amount
of light than others. Separate from this is the
channel selection: if you’re experiencing
interference, you can select a different
radio channel.
All of these changes are made on the master
unit, whether it’s a flashgun or a transmitter —
you don’t have to run around adjusting each
slave unit. For example, you can put a flashgun
in a sealed softbox and alter the flash exposure
without having to remove the diffusion panel.WHAT WAS ONCE AN
EXPENSIVE AND EXOTIC WAY
TO TRIGGER A REMOTE
FLASHGUN OR STUDIO LIGHT IS
NOW MASS-MARKET STUFF.