Paul C. Buff, Inc. Technical Forum

The CST has to be sitting properly in the shoe because (a) it fires when shorting across the mono plug, and (b) I get 3V DC across the mono plug.

The polarity of the 3V DC, by the way, is the same whether the adapter holds a speedlight or a CST.

hmmm. So is your camera set to TTL control, or full manual on the flash control? It could be that when you have a flash mounted, ttl comms are taking place, and the camera knows there is a flash there. When the CC or CST is mounted, there is no TTL signal, and the camera acts as if nothing is connected--no trigger signal at all.

Is the same thing happening with and without a flash in the TT5 hotshoe?

It makes no difference whether or not there's a flash in the hotshoe.

I'm simply trying to get the CST to fire by pressing 'Test' on the FlexTT5, so the intricacies of the camera are completely irrelevant.

You said in your original post that a flash in the hotshoe adapter fired just fine, but the CST and CC do not. So why do you now say it makes no difference?

There is clearly SOME difference. And the flash likely has additional connections being made to and thru the hotshoe adapter. So the driving signals on the OTHER end of the cable may be affected by what you put in the hotshoe adapter. If not the camera, then the FlexTT5. Maybe you need to try their forum, also.

Will the CST fire if the TT5 is not connected to the camera all?

BDP, you're matching my responde to the wrong post. Tech Support wanted to know whether or not it made any difference if there was a speedlight in the FlexTT5's hotshoe mount. I've tested this with and without a speedlight in the TT5's mount, and it has NOT made any difference.

To be clear, I have taken the camera totally out of the equation by disconnecting the TT5 from the camera. A hotshoe adapter to 3.5mm mono plug is connected into P2 on the TT5. As I understand it, pressing "Test" on the TT5 completes the circuit between the center pin and the metallic slide on the hotshoe adapter. Bingo, the flash fires when pressing "Test". However, if the flash is replaced with a CST, the CST does absolutely nothing.

I was associating your response with both our posts, since you mentioned that intricacies of the camera did not matter, which went to my question, but had not mentioned that you had disconnected the camera.

So, the Flex is what sees a difference between the flash and the CC/CST. Take a bit of scotch tape, cover the four small additional connections on the hotshoe adapter, try the flash again.

My bet is that the flash will not fire in this case, meaning it is somehow making use of those connections to determine that there is something in place to send a test fire signal to.

Since you can fire the CST by shorting the connection, you know the connection itself is good, so the TT5 must not be sending the signal. You know the TT5 is capable of sending the signal because when you put a flash in the adapter, it fired.

So the TT5 is, for some reason, not sending the signal when a CST is installed. Covering those contacts would prove whether or not they are a factor in this. If you have a cheapo flash, with only the center contact, you could also try it out, see if it fires or not.

(an aside: David Hobby recently discovered and posted that covering certain hotshoe contacts with scotch tape would allow the d7000 to fire a nikon flash at any speed, rather than limiting it to synch speed in normal mode. the dark band is not always a factor, so he wanted a way around that firmware limitation. kinda cool)

I put tape over everything except the center pin on the adapter cable, and the flash still fired. I removed the tape and did it again to ensure that all the pins (sans the center pin) were covered.

I have 2 FlexTT5's, which we can call PW-A and PW-B. I slid PW-B into the hotshoe adapter, and plugged the mono end into P2 of PW-A. Press "Test" on A, and guess what? It doesn't fire. So, a flash can be fired when all pins are covered except the center pin, but another trigger (CC/CST/TT5) won't fire.

The only remaining difference I can see wrt to connections is that the CST only has a center contact, and does not have a contact to the to the larger metal contact plate but does have some small metal sections inside the side "grooves" of the plastic foot that should make contact with rails of the hotshoe adapter. If those are not making contact, or not reliably making contact, that could prevent firing. Try putting a little twist and hold on the CST, see if that makes any difference. Since you were previously able to fire the CST in the hotshoe mount without the Flex, this is unlikely to be the issue, unless the connection is tenous and intermittent.

It really might be worth a call to their tech support. Other than a last ditch move of putting a brand new battery in the CST, which doesn't seem plausible, as you have the same problem with your CC, I can't think of any other troubleshooting steps right now.

Does the TT5 have a metal foot like a speedlight? Since it works in the adaptor, that might be one last clue. It likely makes a more solid contact.

Okay, one last idea (includes a question for PCB TS). Does the connector jack on the side of the CST work as an alternate trigger INPUT, or just as a trigger output?

If it serves as an input, perhaps a cable direct from the Flex will fire the CST, and this connector likely makes better signal and ground connections. That might be another useful data point. The rail connection might not be solid enough. Does the CST feel at all loose (side to side, any twist possible, etc?)

The CST and CC fit just fine in the shoe of the adapter cable, and this is confirmed because I consistently get 3V across the mono plug.

The connector jack on the side of the CST does serve as in input trigger. When I first discovered that the hotshoe adapter cable wouldn't get the job done, I made a 2.5 to 3.5mm mono cable to see if that would work. Plugged the 2.5mm end into the CST, and the 3.5mm end into P2 of the FlexTT5, and (drum roll)......nothing! I'm wondering if there's something odd about the CST/PW combination, like maybe the CST needs a longer trigger duration than what's coming out of the PW.

I exchanged mail with the folks at PW, and all they've said is "it should work".

The main objective is to use speedlights and Einsteins at the same time. PW developed some very capable products (TT1 and TT5) for extending CLS functionality, and we already know how great the CC/Einstein combination has turned out to be. Even though there will be some constraints, why not take advantage of both? There is, of course, the option of placing a CST directly in the hotshoe of a TT5, although that's an expensive solution because it dedicates the TT5 to simply triggering a CST.

I'm surprised that someone at PCB didn't immediately know the answer to this issue, or at least get their hands around it in short order.