Canon 1V, Pocket Wizards, and a Vivitar 285

[Tim Gray]

I asked this over on photo.net but didn't really get any useful responses ("turn off the E-TTL on the flash"). I'm guessing not many in the Canon forum over there actually use 1V's anymore...

I was playing around with my 1V, Vivitar 285HV, and Pocket Wizards last night. This is the first time I've played with this setup. I have experimented some with the 285 + 1V, but never the PW's. Anyway, I noticed every time I took a photo, the flash was triggered twice, once during the exposure and once right after it. I could see the 2nd flash through the viewfinder, so it's right after the mirror goes up. If I take the PW's out of the equation and leave everything set exactly the same, except for mounting the 285 on the 1V, the flash only fires once, as expected.

On my other camera (M6) the PW only fires the flash once, so it's probably not the PW's, but the 1V.

What gives? Anybody no why the 1V is triggering twice the PW's twice, but not the flash? How do I fix it?

 

[Troy]

Try using a PC sync cord instead of the hot shoe on your 1v, and make sure you're in manual mode not shutter or aperture priority mode.

 

[Tim Gray]

I'll do that. I was in manual mode for sure, but if I only get one flash with PC socket, I guess it's something with the hotshoe. Though I'd ultimately like to use it with the PW in the hotshoe...

 

[John Koehrer]

If the lv has the Canon 5 contact setup try covering all but the central contact with electrical tape just on the off chance it may be something hinky with the shoe.

 

[Tim Gray]

Alright. Update. I tried it with the PW attached via the PC socket and get the same thing. Two flashes for every shutter release. One during the exposure and one right after it.

As far as the contacts, the 1V does have multiple contacts, but since the PW only has a center pin and there is no physical connection to the other pins, can't see how that would help. Regardless, it does it through the PC socket, so its not a hotshoe problem, but presumably a 1V problem. The thing that confuses me is that the 285HV mounted directly on the camera doesn't exhibit this behavior...

 

[Tim Gray]

Sorry to dig this back up again, but was wondering if anybody had any more insight.

 

[zenrhino]

Sorry to dig this back up again, but was wondering if anybody had any more insight.

Tim, let me see if I have the scenario right.

If you put the flash ON the shoe, it fires just fine.

If you put the PW transmitter (transceiver if you're wealthy) in the shoe and use the receiver to trigger the flash, you get a double flash.

If you trigger the PW transmitter from the PC synch and use the receiver to trigger the flash, you also get a double flash?

Let's start eliminating things:

Do your PW's work fine on other cameras?
If you use a PC-to-Viv cable to fire the Viv off-camera does it only gives 1 flash?
Have you done (I would presume so) a test to make sure that if no camera is hooked up you still only get 1 flash by using the test button on the transmitter?

 

[Tim Gray]

> If you put the flash ON the shoe, it fires just fine.

Yes

>If you put the PW transmitter (transceiver if you're wealthy) in the shoe and use the receiver to trigger the flash, you get a double flash.

Yes. They are the PW Plus II's - and no I'm not wealthy

> If you trigger the PW transmitter from the PC synch and use the receiver to trigger the flash, you also get a double flash?

Yes

>Do your PW's work fine on other cameras?

Seems to work as expected on my Leica and my Canon Digital Rebel.

> If you use a PC-to-Viv cable to fire the Viv off-camera does it only gives 1 flash?

This I haven't tried. I'll try it tonight.

>Have you done (I would presume so) a test to make sure that if no camera is hooked up you still only get 1 flash by using the test button on the transmitter?

Yes, this works as expected. It really seems to be a 1V problem...

 

[Tim Gray]

Ok, I tried the Viv flash connected to the 1V with the PC-viv cable and that worked fine too. The only 2 combinations that are funny are Canon 1V + PW + flash, and the PW are triggered either from the hot shoe or PC. The flash works fine hardwired directly to the camera, and the PW's and flash work fine with other cameras, including a canon dslr.

I also wrote Canon. They said it was PW. Thanks guys. I then wrote PW. They said some cameras deliver 2 sync pulses, one with the shutter opening and one with it closing. I don't see why this wouldn't trigger the flash when it was hard wired then...

 

[zenrhino]

Ok, I tried the Viv flash connected to the 1V with the PC-viv cable and that worked fine too. The only 2 combinations that are funny are Canon 1V + PW + flash, and the PW are triggered either from the hot shoe or PC. The flash works fine hardwired directly to the camera, and the PW's and flash work fine with other cameras, including a canon dslr.

I also wrote Canon. They said it was PW. Thanks guys. I then wrote PW. They said some cameras deliver 2 sync pulses, one with the shutter opening and one with it closing. I don't see why this wouldn't trigger the flash when it was hard wired then...

Wacky.

Ok, seems like the next logical step would be to get your hands on another camera (same model, etc) and try your PW's and flash on that camera.

Barring that, maybe you can hook a voltmeter to your shoe or pc socket and see if it really IS throwing two sync pulses? That kinda makes sense since Im assuming your camera has a rear sync option on it so maybe theyre throwing both pulses and only using the one they need?

 

[Tim Gray]

Even if the camera is throwing out 2 syncs, how come the flash hooked directly to the camera doesn't trigger twice?

I'll scope my camera this weekend. Should be easy to see what's coming out of it.

Anyone live around Philly with a 1V who wants to let me try it out with my equipment?

 

[Tim Gray]

I scoped my camera. It appears that the center pin to the edge of the hot shoe (ground in this case?) has 0 V in standby mode. When the shutter is half pressed for metering, the center pin jumps to approximately 3.3V and stays there until the in camera metering shuts off. When shutter is press down all the way, the center pin drops down to 0V and rises back up to 3.3V approx 200ms later. I say approximately because as the shutter speed gets faster, this gate narrows a bit (10 ms or so) and as it gets longer, say 1/15s, the gate stretches out to about 300 ms, 1/5s was around 380 ms, and at 1s, it was 1.16 s. The PC port showed the same behavior.

I guess the PW is interpreting the leading and trailing edge of the gate as a trigger. If this is the case, I don't know why it's not interpreting the voltage rise at the beginning of metering (and at the end of metering for that matter) as a shutter trigger. So I must be missing something. The 285HV knows how to interpret the signal in the hot shoe. And the PW knows how to interpret the M6 signal (which I need to scope). I didn't scope my M6 since it has film in it right now. I'll do it the next time its empty. Actually, I didn't think of it, but will now.

For that matter, I'll scope the pulse that the PW generates too.

 

[ozphoto]

I've had a similar problem with a Nikon D2xS. Ok, this model is d******, but the problem's the same. Only intermittently, but I've come to the conclusion it is the actual synch cord as I can wiggle it around a bit and it disappears.

I use the PW II with the settings set for "BOTH" on each. Is that how yours are set?

-Nanette

 

[tim_walls]

I'm curious what you were measuring on your camera; centre pin to ground should be the anode-to-cathode of a thyristor in a camera like that I believe. You must be measuring the gate voltage.

You should be measuring resistance/continuity, not voltage - when the gate voltage is applied to the thyristor it closes the pin-to-shoe circuit which is what triggers the flash.

If you are measuring thyristor gate voltage, it should match - but you may confuse yourself if you check another camera which uses a mechanical flash trigger switch and you can't find the volts .

All my own speculation, by the way, corrections gratefully accepted


Further pondering... A thyristor latches of course; one it's been triggered to conduction by the gate voltage, it will continue conducting until (a) the gate voltage is removed and (b) the anode current drops below a threshold. In practice that means the 'falling edge' of the gate pulse is irrelevant when you have a real flash connected; once the thyristor is triggered it will conduct anode->cathode until the stored energy in the flashgun is fully discharged through the flashtube (at which point the anode current drops below the point at which the thyristor stops conducting until it's triggered again.) (A good old fashioned flash just connects the output of its storage capacitor directly to the centre pin, and the input to the flashtube to the edge pin - the thyristor/switch just connects the two together so the capacitor discharges through the tube. That's why old fashioned flashes present a few hundred volts on their centre pin.)

 

[John Koehrer]

This may be another bit of useless information but......Is there a safety switch in the hotshoe? Most cameras do have them. Usually between the tension spring and the edge of the shoe. You can usually see the plastic post by peering into the edge of the shoe. The safety switch should be closed when you're testing.
Your knowledge of electronics is way beyond mine and especially with one of the newer(?) old cameras like this. With a mechanical switch it's just an NO switch. I do like the idea of the double pulse causing your quandry.
In the past I've seen a number of odd occurrences with the Canon SLR's including flash units that would work on other cameras. We assumed it was polarity differences & let it go.

 

[Tim Gray]

Ahh, see I come from a science background and was thinking of triggering, which is usually 5 V TTL pulses or gate pulses. I'll remeasure the impedance. I figured since Canon cameras have fancy communication with their flashes, there must be some stuff going on voltage wise. The thyristor makes sense.

It's odd that other people don't seem to have this problem, since there must have been at one time a lot of 1V's in use, and they must have been used with PW's. I'd also be surprised if the way the hotshoe works in a 1V (a modern camera) is that different from the new digital models.

And yeah, I was measuring from center pin to the edge.

 

[tim_walls]

There is plenty of other clever stuff going on voltage wise, but it should be via the other pins on the hotshoe. The basic hotshoe cirsuit is centre-pin to shoe, normally open closed when the shutter fires. (Of course, I wouldn't be surprised if certain signals on the other pins changed the behaviour of the center pin on an intelligent camera like the 1V.)

Assuming what you were measuring was the gate->cathode voltage though, everything you measured 'looked right'. You would expect a pulse when the 1V meters (my 1V fires the flash whenever I take a sample, at least in multi-point spot, which is what I normally use,) and then another one when the shutter fires (of varying duration, although in principle anything attached should pay attention to the rising edge only - there are no guarantees of what the falling edge will do AFAIK.)


Hmm. That's a point. Does metering mode make a difference? When I'm spot metering, the flash fires whenever I take a reading, but I don't remember getting a double flash when shooting in one of the other meter modes...

 

[Tim Gray]

No, metering mode makes no difference. Again, to reiterate, everything works fine with the flash mounted directly to the camera. Its when the PW's are in line, they interpret the 1V's signal as 2 flashes, one at the appropriate time, and one after the shutter closes. I did some tests with long shutters speeds, and the second flash is most definitely after the mirror goes back because you can see the 2nd flash through the viewfinder.

 

[tim_walls]

humph, I'm confused then - the signal you measured sounds correct, so I assume either the PW is faulty or it's trying to be too clever by half (I've never used a PW - is there anything configurable about them?)

I've tried to recreate the problem with my 1V, a Vivitar 283, and with/without cheap wireless triggers, and I can't.

I have a scope and a logic analyser here - if you want me to make any measurements of my 1V to compare let me know.

 

[Tim Gray]

Cool. Yeah, I have no problems with my 1V and 283. Its just with the PW inline. I might get back to you about measurements in a bit. I'm going to do a bit more investigation first.

 

[Vanishing Point Ent.]

Check the Synch Polarity.

O.K., try this, connect the pocket wizard to the Nikon screw lock, use a paramount cord. Now when you connect the Household side to the Pocket Wizard & try it.

If it solves the problem, fine. If it doesn't, as I suspect, reverse the HouseHold connection. I know, that because of the polarized plug, this won't be easy, or maybe not even possible, but try. I think, that you'll find that this is a polarity problem. You may have to file down the wide blade of the cord, you just bought. If you do, use liquid paper, to mark one side of the connection, on the cord & the matching side on the Pocket Wizard.

Remember to try both Pocket Wizards & both cords. The one connecting the camera to the PW transmitter & the one connecting the flash to the PW receiver.