Sunday, March 7, 2010

AC5 Soft Shield Distance Test

In late 2009 Pocket Wizard starting shipping free* AC5 soft RF shields to address the the problems between their FlexTT5 triggers and Canon Speedlights. The AC5 is essentially a sock made of RF shielding material which surrounds the flash and is cinched off to an RF shoe filter provided as part of the kit.

The RF noise from some Canon flashes were interfering with the radio frequencies used for communications between the MiniTT1 (master) and the FlexTT5 (slave) triggers. The RF interference impacts the distance you can remotely trigger your flash units. To see how much of a difference this solution would make, I performed a quick test to measure the effective distance of the units with and without the AC5 solution. Prior to testing I installed the latest firmware version 5.0 available from PW. I place a FlexTT5 and 580ex II on a light stand at the end of a standard narrow apartment / condo style building hallway and backed off until I lost reliable communications between the camera and the flash.  Here are the results I obtained:
FlexTT5 FlexTT5 + AC5
Distance in Feet 40 100+

 The hundred foot limit might be related to a metal door frame I encounter in the hallway (the door is used as a fire break). It seemed that once I crossed the threshold of the frame I lost reliable communications.

 Pocket wizard has started including the AC5 soft RF shield with all FlexTT5 units sold and is about to start selling an AC7 model which is a hard plastic version. From early product images of the AC7 it appears to allow easier access to the flash controls (bonus for manual flash users) and has two lightstand/bracket mounting points. No information is provided at this time if the AC7 will provide any increased usable distance over the AC5 model.

* offered until 30-Jan-2010