Saturday, January 5, 2013

The RadioPopper System: My Experiences

   Although there is plenty of technical information on the two RadioPopper (RP) systems on various web sites (e.g. RadioPopper, Strobist, Flickr: Strobist), there isn't as much information regarding the JrX and PX systems in terms of general usage and operational characteristics.  Hopefully my personal experience with both of these systems can add another perspective for those considering remote triggers for their Nikon or Canon flash units.  Not only are both systems described in terms of their individual operational characteristics, but the characteristics of using both systems simultaneously is also described.  This article is prefaced by noting that these are nothing more than my opinions.  There are certainly users out there that would not agree with some (or all) of my opinions and conclusions.

The JrX Studio System

   At some point it became apparent that the infra-red (IR) trigger line-of-sight system for Nikon flash remote control was not working for all of my needs.  The IR system reliability was just too low in some situations, particularly outdoors.  Plus, I wanted the ability to put the remote flashes behind barriers.

   Not having the funds or the need (so I thought) to invest in a TTL-based system, the RadioPopper JrX Studio system was quite appealing.  The JrX system allows full manual control of certain flash models from the camera using simple knobs.  There at first appeared to be several advantages to this system:
  • Simple transmitter and receivers
  • Connections through the hotshoe (should be reliable)
  • Very simple adjustment controls on top of camera (knobs)
  • Small transmitter on camera (no need for commander flash!)
  • Low cost
  • Possible to control multiple flashes from a single receiver
  • Good on-line reviews 

Using the JrX Studio System

   While the system seemed to be generally quite reliable, it was not 100% reliable as expected.  The connections through the mini-stereo connectors would on rare occasion be finicky.  Although the problem was fairly easy to remedy by cleaning the connectors or jiggling the plugs, it was still a pain.  Note that this issue did not occur on a regular basis in my case, but it did occur.  With three pieces of hardware required for each receiver (receiver, cable, RPCube), there are at least three possibilities for a bad connection.

   A more significant concern for me was with the JrX system's lack of fine-tune control with the transmitter knobs.  When controlling SB-800s, for example, it seemed like a very small turn of the knob could result in a large change of power at the remote flash.  I used a light meter to attempt to calibrate the knob so that more accurate adjustments would be possible, with the intent of making a label.  A listing of those measurements is given in Table 1. It was surprising how much the light output would change for a given rotation of the knob in one region - two stops between 135 and 180 degrees.  On the other hand, the same turn in another region would not make much as much difference - one stop between 90 to 135 degrees.  That is, the output was not very linear with changes in knob position.  While 45 degrees may sound like a lot, it really is not that much for the very small knobs on the transmitter.  When one is trying to fine-tune the flash output, this lack of accurate control was sometimes an issue for me - though not necessarily a deal breaker.

Table 1. JrX transmitter knob position and measured flash output for SB-800 and Studio Receiver

   In terms of setting up a multi-flash lighting configuration, it can be somewhat cumbersome to use a light meter with the JrX system.  One can fairly easily use a light meter to adjust the first flash group output by simply setting the other group levels to zero.  The issues arises when attempting to adjust the output of subsequent groups without interference from the first group.  There is no convenient way to disable the first group from the transmitter without turning that knob to zero.  Of course, if one turns the level for the first group to zero, then it is extremely difficult to put it back where it was before.  In my opinion, RadioPopper should add toggle switches for each group allowing them to be disabled.  Again, these opinions are based on my observations.  Others may not find this to be a big issue.

  As I moved to prime lenses with faster apertures, the lack of AutoFP (Nikon's high speed sync) with the JrX system became a bigger issue when photographing outside during the day.  The JrX system is not designed for shutter speeds above 1/250 (depending on camera model).  Nevertheless, I wanted the ability to perform high-speed sync with radio triggers.  The lack of AutoFP was the primary factor that pushed me towards adding the PX system to my camera bag.  The addition of TTL control is also nice.

The PX System

  The PX system allows full TTL and manual control of remote flashes since the system continues operating in the native Nikon CLS language.  The remote simply relays the IR signals from the commander to the remote flashes via radio instead of line-of-sight.  The cost of the hardware has recently dropped to a level that is comparable to the PocketWizard (PW) system.  The main advantages of the PX system include:

  • Small receiver/transmitter
  • Diagnostic mode for troubleshooting
  • Uses AAA batteries (I use eneloop rechargeable)
  • Full TTL and Manual control
  • AutoFP (high speed sync at shutter speeds above 1/250)
  • Possible to control multiple flashes with a single receiver (more on this in a future post)
  • Possible to control (generic) flashes via JrX Studio receivers (more on this below) 
  • Possible to trigger any flash via JrX generic receiver

Using the PX System

    Before discussing my general observations on the PX system, one very unique feature is discussed that doesn't appear to be mentioned much on-line. The PX transmitter can be used to control the output of certain flash models connected to a JrX Studio receiver.  There are three group settings on the PX Transmitter (G1, G2, G3) that can be accessed via the menu system.  While the adjustments can be somewhat cumbersome to use, it is nevertheless possible to adjust the levels of each group and subsequently control the output of a remote flash via the JrX Studio receiver.  In a makeshift test using a light meter, I measured the output of an SB-800 connected to a JrX Studio receiver for all 32 levels in the PX Transmitter group setting.  The results are shown in Table 2.  This chart may be of interest to those planning to use the systems together.  Note that by using three CLS groups and three JrX Studio groups (via the PX group setting), it is possible to control the power levels of 6 groups of flashes using a single PX Transmitter!  If one adds a regular JrX or JrX Studio receiver in the D-group, an additional 7th group can be triggered! The ability for so many groups is pretty versatile, though I've never actually used that many.

Table 2.  Measured SB-800 output levels for given Group Level setting on PX Transmitter.  SB-800 connected to JrX Studio Receiver. 

    In terms of reliability, the PX system (receiver shown in Figure 1) has been quite reliable.  The PX system is still not a perfect system, though.  There are a few things that at times have made me wonder if I should eventually switch to the PocketWizard system.  For the time being, though, I plan to stick with the RadioPopper.  A summary of things that I believe could be addressed in future designs is described below.  As noted above, this is all based on my usage and opinion and therefore may not be an issue for other folks.

Figure 1.  Small PX Receiver

   One issue I see with the PX system is the manner in which the receiver mounts to the remote flash. RadioPopper (RP) developed brackets that make mounting the receivers fairly easy.  However, the Nikon brackets are huge, as shown in Figure 2 next to a regular SB-800 foot.  The brackets were designed to be easily reconfigurable for different flash models.  As a result, the brackets naturally fall apart when the flash is removed, which can make for additional handling.  Because the brackets are so (unnecessarily) large, one would need a much larger camera bag to carry these awkward brackets along with multiple flashes.  Since I rarely do studio-type shoots, I did away with the brackets and reverted back to the velcro approach as described later.  Now all that needs to be transported are the flashes and the small receivers.  Even though the bracket problem has been addressed using velcro, I still feel the PocketWizard (PW) approach of attaching through the hotshoe is much cleaner.  Of course, in using the PW approach there is always the potential for future compatibility issues.  PW may require firmware updates for newer cameras while the RP system should always work so long as Nikon sticks to IR.

Figure 2.  RP PX Mounting bracket next to Nikon flash foot.

Compact Controllability

   Another configuration option with the PX system is related to what I call "compact controllability."  The PX system always requires some method for controlling the group levels as the transmitter is nothing more a means to convert an IR signal to radio.  It is worth summarizing the various approaches for enabling that control.

RP On-Camera Flash Bracket

   RadioPopper sells a bracket that allows the transmitter to be mounted above the on-camera flash for cameras that have a built in commander mode.  This bracket is shown in Figure 3. While this configuration is pretty compact, the on-camera flash must fire.  In photographing some subjects, this can be an issue with "blinkers." For example, my kid is notorious for blinking with the TTL pre-flashes and thus has her eyes closed when the exposures is made.  While one can use FV-lock, that is just an extra step when using TTL mode.  In using this mounting approach, one must use in-camera menus to adjust output levels of the remote groups.  Furthermore, one is limited to two groups.

Figure 3.  PX Transmitter on RP on-camera bracket.

Nikon SG-3IR Bracket

   Nikon makes an IR filter that can be used to block light from the on-camera flash.  As shown in Figure 4, the PX transmitter can be mounted to the front of this SG-3IR filter using velcro.  While this approch is also compact and eliminates any pre-flash issues with "blinkers," one is still required to use the in-camera menus and is limited to two groups.  Another issue that arises with this configuration is the transmitter flopping out when the camera is placed in portrait orientation.  Nevertheless, this is a great option when desiring to travel light.

Figure 4.  PX Transmitter on Nikon SG-3IR filter bracket.

SU-800 Commander

   My preferred transmitter mounting option involves using the Nikon SU-800 commander unit.  This  unit is very light weight and is fairly compact, as shown in Figure 5.  While this commander does use hard-to-find CR123 batteries, I have found that the battery life is pretty long.  All of the group controls are available on the rear display.  The one drawback with this commander is that when using Manual mode, the output settings for each group are limited to one full stop of adjustment.  That is, one cannot adjust each group by 1/3 or 1/2 of a stop.  This can sometimes be an inconvenience.  Note that when using TTL for a group, the 1/3-stop adjustability is available.

   There is one TTL mode side-note worth mentioning for the SU-800.  This unit has a macro-mode (switch in battery compartment) that can be used to quickly set lighting ratios between the A and B groups.  This is done by simply moving the setting toward one group.  In that case, the output in one group is increased and the other group output decreases.  It is really neat that one can set a ratio right from the display (e.g. 1:3).  There is also an option to add a third group that can be independently controlled. There is more information on this in the SU-800 manual.  I have not found this feature on any other Nikon commander unit.

Figure 5.  PX Transmitter on SU-800 commander unit.

Dedicated Commander Flash

   My least preferred option for mounting the transmitter involves using a dedicated on-camera flash commander like shown in Figure 6.  This is a very heavy and cumbersome way to trigger remote flashes, in my opinion.  If one requires some on-camera flash output, then this is probably the way to go.  However, I rarely require any output from the camera.  To avoid "blinkers," the flash can be turned to face up.  However, this makes the unit very tall and the transmitter antenna sticks backward.  There is the advantage of quick control as the SB-900 menu system can be easy to adjust. Still, the added weight is, in my opinion, a big disadvantage.  As a result, I rarely use this option.

Figure 6.  PX Transmitter mounted to SB-900 commander flash.

   Although there are several options for mounting the transmitter, it would be really nice if RP could  develop a JrX-like transmitter/controller that could be used for manual adjustments of PX receivers.   I believe this is possible on the Canon side, though I was told by RP that it is not possible on the Nikon side - despite what the brochures say.  While making a JrX-like commander would require deciphering the IR language, other manufacturers have obviously been able to crack that language.  PW has a compact transmitter that allows quick and easy adjustments in TTL and Manual modes using simple knobs.  This is one feature that has attracted me to the PW system.  However, I do feel the RP system is more future-compatible proof as it does not rely on cracking the Nikon language.

Using Velcro Mounts

   Before summarizing, I'd like to provide a brief overview of how the PX receivers are mounted to flashes with velcro.  While this might seem trivial or even overboard, the approach has proved quite reliable.  Furthermore, the approach is useful in utilizing a reasonable-cost splitter to control multiple flashes with a single PX receiver.  That topic will be addressed in a very detailed future article. 

  The IR bulb on the PX receiver must be aligned with the IR sensor on the flash.  Furthermore, there must be a pretty good seal to ensure that any stray IR light does not enter that sensor. Interference from any outside IR signal, even if from the commander flash, can prevent the system from operating properly.  The RP provided PX mounting bracket has some fairly dense foam that is used to seal that light - the bracket also provides fairly natural alignment.  However, when using the brackets I did have at least one occasion where light was leaking in through the foam due to slack in the bracket.  The approach I used for the velcro mounting system is shown in Figure 7.

Figure 7.  PX Receiver with velcro and foam pad light seal

  The velcro mounting system involves Scotch® Fasteners Heavy-Duty, which is a velcro-like fastening material.  This fastener is much stronger than regular velcro and does not fray like the fabric velcro.  The Scotch material is all plastic and quite rigid.  In addition to putting this material on the receiver, it must also be mounted on the flash, as shown in Figure 8. Note that enough fastener is used on the receiver so that it can be rotated by 90 degrees, if desired.  I am not sure I have ever rotated a receiver, though.
  To seal the IR light, an on-line article recommended using corn cushions.  I found Smart Sense Small Spongy Corn Cushions at a local store.  On the receiver, the foam cushions are stacked two high, while one is placed on the flash unit.  On the receiver, I also added a very short section of plastic heat shrink tubing that fit perfectly inside the corn cushion foam pieces (see Fig. 7).  I am not sure if these are necessary, but it was too easy not to add them.  Again, this may all seem overboard.  However, a future article will describe a reasonable-cost splitter that can be used with a single receiver and multiple flashes.  This all works well as a system.  Figure 9 shows the receiver mounted on the flash.

Figure 8. Velcro and foam pad seal on SB-800.

 Figure 9.  Velcro-mounted PX Receiver on SB-800 flash unit.

   For the sake of completeness, Figures 10 and 11 show how the PX Transmitter is mounted to the SU-800, which is what I typically use as a commander due to its low weight, size, and features.  Note that some gaffer tape was placed over the IR window on the SU-800.  This is just another measure to prevent leaking IR light from entering the receiver window on the flash units.  Without the tape and when in close proximity to the flash units, interference was observed in a few instances. While one certainly would not need a radio system in this case, I preferred not to have to worry and thus added the tape.  Note that instead of the Scotch fasteners, small velcro pads that are available at most home supply stores were used  on the SU-800 and transmitter.

Figure 10.  Velcro on PX Transmitter and SU-800 Commander.
Figure 11.  RadioPopper PX mounted on SU-800 commander.

Nikon CLS Manual Settings Output

  Since measurements were performed for the JrX system, it also seemed reasonable to perform output tests for the PX system in Manual mode.  Of course, this is nothing more than Nikon's Manual mode and really has nothing to do with the PX operational characteristics.  Nevertheless, the CLS Manual output levels using a remote flash are shown in Table 3.  Again, these levels would not differ from just using the standard Nikon CLS IR system

Table 3.  Measured flash output for conventional Nikon CLS manual settings (regular IR or PX).  This table is provided for rereference only and does not reflect performance of the RP PX system.


   Once I determined that TTL control and Auto-FP were features that I really wanted, I added the PX system to my camera bag.  After that, I found I rarely used the JrX system.  As a result, the JrX system was sold.  Now I exclusively use the PX system with rechargeable eneloop batteries.  While my method for using velcro and foam pads to seal the light may seem cumbersome or ugly, it has shown to be very reliable.  Furthermore, I recently finished customizing a low-cost splitter that will allow me to reliably control multiple flashes from a single PX receiver.  I often gang up 2 or 4 units in a softbox to gain more power and/or quicker recycle times.  An article on that splitter is forthcoming. 

  The PX and JrX systems provide a range of options in controlling remote flashes via radio.  I do wish that RadioPopper would be a little more innovative in providing more advanced on-camera PX controllers so that one would not have to rely on using the in-camera menus or a bulky on-camera commander. While these latter options certainly work, I don't really feel that added bulk or inconvenience is necessary.  The PW system has shown to be truly innovative in this area.  Even though I have considered selling everything and moving to the PW system, I am not sure exactly what I would gain - at least in terms of the resulting image.

   Although some of the above statements may appear critical of the RP system, I should note that I am generally happy with the system and how it performs.  The construction quality of the units seems top notch.  The units are small and light and fit well in a camera bag, so long as the mounting brackets are left at home.  Plus, the ability to use AAA batteries is convenient with the PX system.

As always, I welcome feedback, comments, and questions.

References and External Links

Of Hair Accessories and Corn Relief – Modifying My Radiopopper Receiver Mount
Scotch® Fasteners Heavy-Duty
Smart Sense Small Spongy Corn Cushions
Flickr: Strobist
SG-3IR at B&H Photo
Nikon SU-800 at B&H Photo 

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