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Tip: RF shielding fabric around 580EX, 580EX II doubles new PocketWizard range  
Friday, April 10, 2009 | by Rob Galbraith
One of the knocks against the new PocketWizard MiniTT1 and FlexTT5 system is its relatively short working range with certain remote Canon Speedlites, ones that emit RF noise in the same frequency band used by U.S./Canada versions of LPA Design's wireless units. The most prominent of the affected flashes is Canon's current flagship, the 580EX II, plus its predecessor, the 580EX.

That's the bad news. The good news is the working range can be increased dramatically by swaddling the remote flash in an inexpensive RF shielding fabric called VeilShield. In our tests, the maximum working distance is doubled, or more, with a corresponding increase in triggering reliability at middle distances too.

The idea is simple. If RF noise from the flash is interfering with the FlexTT5's ability to receive a signal from a distant PocketWizard transmitter, squelching flash RF noise helps clear the way for an incoming trigger command. This is how it should work in theory, and as it happens, it's also how it works in practice.

We started with a semi-transparent fine mesh polyester RF shielding material called VeilShield, and created a wrap big enough to fit either of Canon's 580-series Speedlites when mounted on a FlexTT5. Then, we compared the range in both line-of-sight and typical outdoor portrait configurations, plus general indoors performance, with and without the wrap in place.

The line-of-sight improvement was significant. With a 580EX on top of a FlexTT5 positioned in a second floor window, the maximum trigger distance over a ControlTL channel was about 200ft (61m). Adding the VeilShield wrap extended this distance to about 450ft (137m), or more than double the distance of the unshielded flash. This was still well short of a 430EX II, which achieved about 650ft (198m) in the same test, but represents a dramatic improvement nonetheless. The transmitter in all instances was a MiniTT1, sitting on top of a Canon EOS-1Ds Mark III.

The photo below shows our homemade VeilShield flash wrap, around a 580EX.

Veiled: A homemade wrap made from VeilShield fabric, around a Speedlite 580EX. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)

The following two photos show the position of the flash in the window during testing, and an aerial view of the maximum ControlTL trigger distances we could consistently achieve.

In Position: The Speedlite test location, in the second floor window of Little Guy Media's world headquarters. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)

Next, we tried a 580EX/FlexTT5 pointed into a small reflecting umbrella, at a height and angle typical for an outdoor portrait. Without the VeilShield wrap, the maximum reliable trigger distance was about 90ft (27m). With it wrapped as shown in the photo below, the maximum distance jumped to about 160ft (49m). In both cases, the umbrella interior was turned away from the camera, such that the direct path from the MiniTT1 transmitter was through the umbrella and then through the flash itself to the FlexTT5 receiver's antenna.

No Rain: A VeilShield-wrapped Speedlite 580EX, sitting on top of a FlexTT5 and aimed into a Photoflex umbrella. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)

Switching the umbrella to a shoot-through configuration, then turning it so that the path between the MiniTT1 transmitter and the FlexTT5's antenna was not blocked, the maximum distance without the VeilShield wrap was about 100ft (30m). With the wrap in place, the maximum distance increased to about 220ft (67m).

Finally, we placed a 580EX/FlexTT5 on a lightstand on the second floor, then attempted to trigger it using a MiniTT1 from various locations on the main floor and basement. Without the VeilShield, the flash would sporadically fail to fire in pockets of the main floor, and wouldn't fire at all from most locations in the basement. With the VeilShield, the 580EX fired in all locations on the main floor and most areas of the basement too.

Arguably, this improvement is the most telling of the three, because for us, and probably for many of you too, using the new PocketWizards with Speedlites is not really about triggering them from hundreds of feet away. It's really about having the flexibility to place them most anywhere within fifty feet or so, whether on a bookshelf, behind a pillar or some other location that's beyond the reach of Canon's wireless system on its own. In this regard, VeilShield appears to give a decent-sized helping of positioning flexibility to RF noisy Speedlites that need it.

In short, the VeilShield fabric really works. It doesn't, however, bring the range of a 580-series Speedlite in line with the best of the current Canon flashes, the 430EX II. There's a reason for that: despite its excellent shielding characteristics, our flash wrap is tackling only one half of the RF noise problem. It suppresses much of the RF noise emanating outwards from the flash body, but it filters little of the noise passing through the flash's shoe pins directly into the FlexTT5. We've been able to achieve substantial improvements using the VeilShield material, but a more complete solution also requires RF filtering where the flash and the PocketWizard meet.

LPA Design has completed the early design work on a shielding product for RF noisy Speedlights like the 580EX and 580EX II, one that will provide both flash body and shoe filtering. The net result, says LPA Design's Jim Clark, will be an even more pronounced increase in usable range than what fabric like VeilShield can achieve on its own. The company has not set a firm price or ship date for their RF shield accessory, but it's expected to be relatively inexpensive and have an open back design so that the flash's LCD and controls remain accessible.

In the meantime, the VeilShield material gives PocketWizard users a bonafide range and triggering reliability boost, one that better permits the use of certain RF noisy Speedlights with FlexTT5 receivers. We ordered it from Less EMF in Albany, NY; the company is a purveyor of shielding and measurement devices for every electromagnetic occasion. They ship worldwide. As of this writing, a 58in x 12in (147cm x 31cm) cut piece of VeilShield is US$18.95 plus shipping. From this size you can make a minimum of two double-layer flash wraps.

Making your own VeilShield flash wrap

The flash wrap we used in generating the test results for this article is 12.5in (32cm) x 10.5in (27cm). The first dimension is the height, and is sufficient to provide some overhang at the top of the flash head of the 580EX or the slightly taller 580EX II. The second dimension is the width, and is more than wide enough to allow overlap when wrapping, even with the head tilted and twisted a bit.

Because of its strong shielding properties, one layer of VeilShield around the flash is probably sufficient. But the wraps we've made, and used for all testing, contain two layers, so we can't say for certain that one layer will do the job.

We started with a single 25in (64cm) x 10.5in (27cm) piece of fabric, laid it out horizontally, then folded one end in from the left and the other in from the right, to meet where the strip of gaffer tape is in the photo below (the strip runs all the way around the front and back). The tape holds the two ends together, and also gives the fabric some stiffness that makes it easier to wrap the flash. The tape strip is located not in the centre but about 2/3 the way up the fabric, so that when in place the taped portion is around the flash head and not in front of the LCD.

At some point, we'll probably experiment with adding a stiffening tape strip or strips horizontally too, and doing something with the side edges, which are currently not sealed (but don't really flap open on their own, owing to the nature of the polyester used in the VeilShield fabric).

The red mini-bungees are from Think Tank Photo's Cable Management 10 accessory pouch.

Wrap Star: Our homemade Speedlite wrap and mini-bungees. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)

Notes and tips

To achieve the maximum RF shielding benefit, the VeilShield fabric must be grounded. The simplest way is to tightly wrap the fabric at the base of the flash so that it touches the metal edges of the FlexTT5's hot shoe. Keep it touching with the help of a mini-bungee or similar tie down accessory.

Stopping the wrap short of the top of the Speedlite, as shown in the photo below, reduces its shielding effectiveness slightly. We experimented with a design that didn't quite reach the top of the flash (as shown below), and one that went beyond the head of the flash (as shown earlier in the article), and the latter gave about 10% more range in the line-of-sight test. As a result, all subsequent testing was done with the taller wrap design.

Wrap It Up: A VeilShield flash wrap design that stops short of the flash head opening. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)

Keep the VeilShield fabric away from the FlexTT5's antenna. You can accomplish this by wrapping the flash snugly, and by orienting the flash head, FlexTT5 and its antenna to keep the two as far apart as possible in a given configuration. In testing, we quickly figured out that if the VeilShield material was very close to the antenna it would cause a range reduction that partly offset the benefit of using it to wrap the flash.

We conducted the line-of-sight range testing with both the 580EX and 580EX II. The results were very similar but not exactly the same: the 580EX II's range was slightly shorter in both unwrapped and wrapped tests. Given that the results were extremely close, plus the fact that LPA Design has previously evaluated the RF noise characteristics of the two Speedlites and found them to be effectively identical, the slightly different results are probably explained by either some unit-to-unit variations in the amount of RF noise emitted by Canon's top Speedlites, or by a measure of variability that is an inevitable part of this sort of real-world wireless test. Ultimately, we chose to do the lion's share of testing with the 580EX only, on the assumption that the results apply equally, or nearly so, to the 580EX II too.

Update, April 24: LPA Design has done additional RF noise testing of a large group of 580EX and 580EX II flashes, of various vintages in various serial number ranges. The testing revealed a fairly big variation in RF noise from unit to unit, both in its intensity at PocketWizard frequencies and how wide a frequency band it covers. This probably explains why we saw a range difference between our own 580EX and 580EX II, and further suggests that you might not see identical results from VeilShield with your same-model Speedlites. That is, your absolute range might be more, or less, than what we measured, depending on how RF noisy your units are when compared to ours. Hypothetically, then, if our 580EX can do 100ft (30m) and yours can do 75ft (23m) under the same conditions, and adding a VeilShield wrap to ours increases the range to 220ft (67m), then yours should increase proportionally to 165ft (50m).

The effectiveness of the VeilShield wrap may be reduced slightly when the flash is powered by an external battery pack. With a cable running from the high voltage port of a 580EX down to a Digital Camera Battery, we saw slightly reduced range in the VeilShield line-of-sight test. This could be for several reasons: the battery cable might be a source of interference, or it might also be because it's impossible to wrap the VeilShield tightly around the flash body when the cable is attached. The range reduction we saw might be solvable by tweaking the design of the wrap to better accommodate the battery cable, and perhaps by using some excess VeilShield material to create a wrap for a portion of the cable too. 

All testing was done with U.S./Canada PocketWizard versions. All PocketWizards sold in the U.S., Canada and a handful of other countries operate in the 340-354MHz frequency range. Testing for this article was done only with these versions, and the range results we state are applicable only to these versions as well.

PocketWizards sold in Europe, Australia, New Zealand and many other countries operate at 433-434MHz, and are less affected by Speedlite RF noise from the 580EX, 580EX II and 430EX. They are not unaffected, however, and so may also benefit from a VeilShield wrap, but we haven't tested that.

You can read more about this in a previous article. A country-by-country list of the frequencies used by PocketWizards is here.

We have not tried a VeilShield wrap with a 430EX. As the Speedlite that emits by far the most RF noise at PocketWizard frequencies, it will likely benefit from the VeilShield treatment too. But we haven't tested it.

VeilShield is not the only fabric that provides RF shielding. Less EMF sells a full range of other fabrics as well, and we in fact got samples of all of them, and large pieces of two of them, before settling on VeilShield. Its combination of shielding effectiveness, rip resistance, light weight and transparency (the LCD can be read easily through several layers) made it an easy choice. Feel free to try some of the other materials shown on Less EMF's EMF Shielding & Conductive Fabrics page; the only one you needn't waste time with is NaturaShield, which we tried and quickly ruled out because of its comparatively poor shielding capabilities.

If you're really in a bind, several layers of kitchen aluminum foil around the flash body, with part of it touching the metal edges of the FlexTT5's hot shoe, also provides an RF shielding benefit. Our quick testing suggests that the range improvement is relatively small, however.

Speedlite RF noise impacts PocketWizard signal reception, not transmission. In this way, you can use any compatible Speedlite you want in the shoe of the MiniTT1, or a FlexTT5 acting as a transmitter, since Speedlite RF noise doesn't impact the sending of trigger commands, only the receiving of them. Therefore, no VeilShield wrap is necessary on the transmit side of things.

There are other ways to keep Speedlite RF noise from interfering with incoming PocketWizard signals. We've mentioned these before, but they bear repeating. Mounting the FlexTT5+Speedlite combo on its side, swiveling the flash head backward and turning the FlexTT5's antenna upward will increase the working range because it gets the antenna that much further away from the RF noise source. The improvement is not anywhere near as much as what a VeilShield wrap will provide, but it's something. What we're describing is shown below.

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Sideways: A 580EX II and FlexTT5, oriented to slightly reduce the amount of flash RF noise interfering with the wireless link. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)

Extending the distance between the flash and the FlexTT5 using a Canon Off-Camera Shoe Cord OC-E3 can also help. But only if you attach a clamp-on ferrite core to the cable (close to the flash end). Without the RF filtering ferrite core you can expect little to no improvement, because the RF noise will travel right on down the cable from the flash to the PocketWizard. In addition, the FlexTT5 has to be positioned so that it has a good chance of receiving a signal; if you let the FlexTT5 dangle down the OC-E3, close to the ground, then range can suffer rather than improve. That's because the earth is a strong RF signal absorber. Placing the FlexTT5 on top of a second light stand will give the best result in this situation.

But doing this is a pain. In fact, the reason we opted to experiment with RF shielding fabrics in the first place was in the hope that one of the fabrics would be a viable alternate workaround to the OC-E3+ferrite core+second light stand routine. Happily, VeilShield does the trick. In time, we'll know whether it will be sufficient for most or all situations where we need to use a 580-series Speedlite as a remote flash on a FlexTT5. Based on how it's performing so far, we're optimistic that it will. At minimum, it will carry us through until LPA Design's own more complete shielding product comes available.

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