How to: Add a Sync Port to a Canon 580EX Flash

[Update: As mentioned in my post here, FlashZebra.com has begun selling replacement foot assemblies for the Canon 580EX with the sync port pre-installed! Now you can add a sync port to your flash without worrying about drills and soldering irons... -RRD]

Shame on Canon... Shame indeed! How is it possible that a company's high-end hot shoe flash *not* have an option for remote triggering outside of the optical slave? Given how simple a flash trigger is, including a simple PC Sync port to the flash could have easily been done at the factory... Especially since Nikon's flashes (like the SB-24) have one! To their credit, the 580EX II has a PC sync port ...so you could either drop $500 on one of those or follow this guide.

So what we'll do today is add our own sync port to the Canon 580EX flash with a basic mod. A standard 3.5mm mini-plug jack will be fitted to the bottom of the flash just above the hot shoe. We'll simply wire this to the existing ground and trigger leads & just like that we'll have a fully functional sync port for our 580 allowing us to sync with any remote trigger from a Pocket Wizard to the cheap eBay remotes. The choice of a mini-plug over a PC port was simple: mini-plugs are both readily available and highly reliable. The same cannot be said of the PC connection.

You can pick up a jack like this at most any electronics store, such as Radio Shack, and you can pick up PC-to-mini-plug cables at most lighting supply outfits. I had my cables made by my friend Lon at Flash Zebra. He can make just about any kind of connection that you can dream up; shoot him an email & let him know what you need.

Note - What you're about to see almost certainly affects your ability to use the manufacturer's warranty. This blog is not responsible for any damage you may do to your flash or yourself - keep in mind that soldering irons are hot. You can click on any of the images to see a larger version.

Step 1: Remove Flash Foot
The first thing we'll need to do is to take off the lower-most portion of the flash which contains the hot shoe foot. If you look at the bottom, you'll see four Phillips head screws; remove them carefully and put them somewhere they will not be lost. Now, disconnect the wires running from the foot to the body of the flash & set the unit aside for now. What you're left with will look like this (with the exception that I began drilling just before taking this picture):


Step 2: Drill a Hole in the Foot
This is one of the more unnerving parts of the whole project since you're playing for keeps: we need to drill a 1/4" hole in the foot in order to mount the jack. Choose your location carefully - you want to have enough clearance from the thumb ring and you also need to make certain that you'll still be able to attach the foot to the body without your new jack getting in the way on the inside.


Step 3: Test Fit
Now that you've made your hole, it's time to fit your jack onto the foot so that you can check for clearance issues. (Of course, you'll have done the best you can before cutting the hole, but we're working in such a small space that it's hard to be certain.) Once I fit mine I found that I did have a little bit of a problem clearing some of the internals of the flash body. It was very close, so I took care of it by using my Dremel tool to remove a bit of the plastic housing that my jack shipped with. Once the jack is fitted, it should look something like the following.



Step 4 (optional): Jumping a Stereo Jack
If you got a monophonic jack then you can skip this, but the smallest jack I found happened to be a stereo mini-jack. Since we'll be using mono cables for this it seems wise to jump the contacts for the sheath and ring together. The first step is to determine which leads on the jack need to be combined. The easiest way to do this is to plug a 3.5mm monophonic mini-plug into your jack and then use the multi-tester to see which contacts have become connected together.

The long lead is going to be the common (sheath) connection and in our case the lower lead is the ring connection (if viewing the pins from the top down with the long lead on the left). Jump these to leads together using a small section of wire.

I still am debating on whether or not this step is at all necessary, but it seemed like a good idea at the time.

Step 5: Solder on the Wires to the Jack
If you haven't already, remove the jack from the foot for easier access (and so that you're less likely to drop solder into it). Connect two short lengths of thin-gauge wire to the long lead for the sheath and the short lead for the tip. Solder those connections in place so that they won't come loose. It'll look like this when you're done.


Step 6: Connect Leads to Foot
Now that the jack is wired up, it's time to connect the other ends of the leads to the hot shoe connections on the foot. After reinstalling your jack, route your wires so that you can get the tip lead to the center pin of the hot shoe and the sheath lead to the hot shoe ground. [NOTE: The ground on the shoe is actually on the side and connects to the rails - look between the thumb ring and the flat piece that slides under the rails and you'll note a metal connector in the middle. That is the ground.] A multi-tester is a very handy tool for making certain that you've got the correct locations!

Assuming that nothing has changed in the design, your 580 flash should have the same configuration as mine shown above. The green wire in my setup is running from the sheath to the hot shoe ground terminal (rail) and the yellow wire runs from the jack tip connection to the hot shoe firing pin (center). Now that you've got your targets, carefully solder your leads to the existing contacts on the circuit board. No comments on my soldering job, please!


Step 7: Test it Out!
At this point you should be able to fire up your flash and test that its basic functions are still intact. Plug the leads from the main body back into the foot, but don't attach the foot just yet in case we need to make some tweaks. Can you trigger the flash with the test button? Good! How about by mounting the foot in your camera hot shoe? Cool! Next, try plugging your PC-to-mini-plug sync cord in and see if you're able to trigger the flash that way. Working? Great!

Troubleshooting
...not working? Double check your connections with the multi-tester and make sure you've got solid contact. If everything is connected correctly an impedance test should show no resistance between the outer part of the PC connector and the ground (side) terminal in the foot. You'll see the same zero resistance between the pin of the PC connector and the contact for the hot shoe firing pin on the bottom of the flash foot. You should see infinite resistance between the outer part and pin of the PC connector - if you don't then you have a short. First make sure that your mini-plug is fully inserted. If that's not it, go back and closely examine all of your connections. This is a very basic circuit, however you are dealing with small parts that can trip you up.

Step 8: Put it all Back Together
Now that everything is functioning properly it's time to reassemble your flash. I put some electrical tape around the jack to ensure that no contact is made with the leads. Then you just put the foot back onto the main housing (remember that we checked the clearance earlier!) and replace the screws. Give your flash one last round of tests and congratulate yourself on a job well done!


Some Thoughts on Port Placement
Ideally I would have liked to have installed the port higher up the body of the flash since there really isn't a perfect place in the foot. After much consideration, I decided that there was not a much better location that was accessible without some major work relocating other innards of the flash. The best place to put it may have been the area that Canon provides next to the port for the external power supply (I believe that is what it is for), but it would have required moving some other bits around. Too much trouble for little gain. Due to the battery compartment taking up so much space things are really crammed into the body of the flash without much clearance for new neighbors.

Through a fairly simple modification, we've added a feature sorely missing from the Canon flash product line. Let's hope a future Speedlight won't require a tutorial like this!