Yongnuo RF-602

1 02 2010

I just bought three more receivers because they performed so well.  These receivers are much cheaper compared to Pocket Wizards.  The main feature I am missing would be TTL.  TTL is Through-the-Lens flash metering.  Without TTL capability, I can’t utilize High-Speed Sync.  HSS can be very important depending on the situation.  For example, an outdoor sports event on a very sunny day.  The sports photographer may still need fill flash but still needs a fast shutter speed to freeze motion.  HSS would be useful then.  Without HSS, I am limited to 1/200 shutter speed.  One day I will be able to afford Pocket Wizards.

Quick background:

Each receiver has a female hot shoe.  I attach a receiver on each flash that I would like to use off-camera (OCF is off-camera flash).  Attaching the receiver to a flash allows radio frequency communication to a transmitter.  I would then attach a transmitter to the hot shoe of the camera.  When I half-press the shutter on the camera, the transmitter sends a signal that wakes up any flash with a receiver that may have idled to sleep.  A full press of the shutter will trigger the flash to go off.  My camera can sync up to 1/200 shutter speed (SS) without seeing the rear curtain in the image.  If I bump the speed up to 1/250 SS I can see a black horizontal void on the image.  That is the rear curtain unable to keep up with the speed of the shutter.

Without radio frequency communication, there’s IR – infrared.  IR usually operates through line of sight but you can also bounce IR signals off anything.  Infrared signals are usually alright indoors.  There’s plenty of surfaces to bounce signals on – walls, ceilings, furniture, or you can place a notebook to bounce into the flash’s IR sensor (assuming it isn’t blocked…by say, a light modifier).  Usually, light modifiers get in the way because the modifiers are constructed in a way that the flash has to be placed completely inside it.

If not infrared, then what?  Some flash features optical triggering.  It means a flash will trigger when it says another flash is triggered.  This means the flash on optical triggering mode has to be pointed in a way so that it can ‘see’ the other flash firing.  There’s a problem with this though.

Remember TTL?  TTL automatically determines what flash power/zoom settings you need when you half-press the shutter button.  The flash also fires test shots (not the camera).  These test shots look like real flashes and it could trigger other flashes on optical trigger mode.  When you take the picture for the real shot, the flashes on optical trigger mode won’t be able to fire because it did not recycle in time (all of this happens within a second or two).

To be continued..

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