UPDATE: New posting on the release of the official Radiopopper RPCube and a Canon DIY cube is here:
I’m a big fan of the RadioPopper guys. I really think they are the real competition for the guys at PocketWizard. The RP guys have had their share of delays, sputters, and poor public relations – at least from where I sit. I suppose that sort of thing happens when a new company that’s new to manufacturing starts up. I will say though that they have held to the highest standards. Many start-ups would have felt the pressure to get something out on the street but they held fast and waited until they could deliver a high quality product. They’ve scored again with the JrX Studio receiver. The JrX is an amazing receiver with great range and reliability but the standout feature is the ability to control Alien Bee studio strobe power from the transmitter. This is a feature of the RadioPopper PX transmitter too but the PX is more complicated to use and is more tuned to TTL flashes.
Quite likely the best feature of the JrX studio is it’s ability to control the power of TTL flashes from the trigger. There’s only one catch, you need something called a “RadioPopper Cube”. The cube will allow the trigger to send a “quench” signal to the flash and shutdown the flash power after an adjustable period of time. The quicker the flash power is quenched the lower the power of the flash. Don’t quench it at all and you’ve get a full power flash.
TTL flashes have a quench pen that allows flash to receive the quench signal. Standard manual flashes don’t have the quench pin or the ability to be quenched – they’re just fire and forget.
Now as cool as all this is, there is bad news. You need a RP Cube to connect to the RP JrX Studio to get the trigger/quench signal and pass it to the flash. The bad news is that once again the guys at RP have not met their planned date to make the cubes available. They were expected to be available 6 weeks after the JrX was made available but that time has come and gone.
The good news is that for Nikon TTL flash users at least, you can make you’re own RP Cube equivalent (or even maybe two) for about $15. The photographers over at the Strobist.com Flickr discussion group figured out how to do it. I read what they had to say, made my own, and took pictures along the way so you can make your own too.
First you need to get a connector with the proper quench pin. The Nikon AS-E900 (I got mine here at BH Photo for $9.95) is a intended to be used with the Nikon Coolpix 900, 950, 990 or 995 digital cameras for use with a more powerful, external shoe mount flash. We’re going to cut it up and make it work with the RadioPopper JrX.
In addition to the AS-E900 you’ll need at least one 1/8 (3.5mm) stereo plug from Radio Shack. The only one my local Radio Shack was this two pack for $3.99.
This is the AS-E900 out of the box. Note the hot shoe and the three pin connector on the other end. We’re interested in the shoe end for now but after we cut the cable in half don’t throw away the three pin end. You might be able to use it depending on what other flash you have.
The first step is to cut your AS-E900 cable in half like this.
Next you need to cut the cover off the cable.
After you remove the cover you need to separate four components inside. There is a braid of small uninsulated wires that are used for the ground. There are also two insulated wires. One will be the trigger wire and one will be the quench wire.
You need to remove the cloth used to strengthen the cable because there won’t be room for it inside the 1/8 inch plug.
Next you’ll strip the insulated wires back about 1/4 of an inch (1cm) and then put a little solder on the wires to keep the them from coming un-braided. This is a good time to slide the plug cover up on the wire before you solder the plug lines in place.
Now connect the 1/8 in plug. You can use a meter to figure out which is which but the ground (braid wire goes to the long center post on the 1/8 inch connector and the two others go either to the left or right small connectors. You’ve got a 50-50 chance of guessing right so I just hooked the shoe to my flash which must be in TTL mode and stuck them in the holes and hit the trigger test button. I got lucky and it work on the first try. I also tried them the other way to see if they would work – they didn’t so I switch them back.
The next step was to solder them in place and clip back the excess wire that sticks out. I recommend that your run the wire from the inside to the outside so the excess is outside. It will be much easier to cut off the extra wire that way.
Slide the wire back in place and you’ll be all done!
The other end of the cable can be wired up the same way and used with an Nikon SB-800 by plugging it into the side 3 pin plug where it will work the same way as the shoe mount above and will look like this when it’s done.
Here it are shots of the shoe connected to a Nikon SB-600 and the 3 Pin connector to a SB-800.
The RP Cube lets me get an amazing range of power adjustment out of my Nikon TTL flashes and my Alien Bees and they can be mixed altogether in one shoot in three groups.
Using my meter, I test the range of the flash output between manual and RP Cube power adjustment and found that they match exactly but I think the knob allows for opportunities to adjust between the manual settings.
UPDATE: I’ve been contacted by several people saying the DIY didn’t work and each time it was because they hadn’t put the flash into TTL mode. You have to be in TTL mode for the quench signal to work! Don’t forget this simple but important step.
UPDATE: Here is a very cool DIY mod much like this setup that uses an internal 1/8 inch plug to eliminate the external cable being hardwired to the shoe. You’ll need a cable to connect to the RadioPopper JrX but this should expand your options for cable length. Nice work Aaron!