RZ67 proII flash syncing with lens x-sync connection

[raccou]

Last weekend I had a modest fashion-shoot and while I normally work 100% with the mamiya and film, this time I only used it at the very end, just to make some pictures of the models who were friends. The lighting was balanced with an umbrella and available light, resulting in a shutterspeed of 1/4th to 1/8th of a second. I was using Pocket Wizards to trigger the flash, and since the hot shoe on the camera body doesn't work, I connected the Pocket Wizard to the lens X-sync connection. Now what happened was that there were 2 flashes, one on the opening of the shutter (normal) and just on closing as well. It's this 2nd flash that had me wondering. It's like a 2nd curtain thing. It's on the negatives, so they're slightly overexposed (flash was just used for fill, so the power was very low), and when the models weren't standing perfectly still, there are double images, so I know the film 'saw' the second flash.

My question now is: could someone verify for me if this is also the case when using the hotshoe? (note: same effect when I connect the flash (nikon SB28) directly to the lens).
If it's not, I'll get the hot shoe fixed, it's quite annoying.

 

[BenZucker]

Ok, So I dont use an RZ67 that often, but I know I have not had this problem before when using the RZ. I would suspect this has something to do with the shutter in the lens and would have the same effect weather or not your were connecting the Pocket Wizard to the pc port on the lens or the hotshoe. I have had lens on a Hasselblad and my view camera lens that do this. My solution has been to use a Pocket wizard multi max and to set the "contact time" to a longer amount of time. This prevents the second flash from happening. Hope this helps.

 

[Rudeofus]

From a pure engineering stand point: I would suggest that the x sync output on your lens is a mechanical contact which bounces on (de-)activation. Your flash (triggers) see the bouncing as second trigger pulse, and since it happens 1/8 to 1/4 second after the first trigger, your flash is mostly charged and will fire a second time at the same power level. Depending on the age and wear of the lens this effect may be more or less pronounced. There are few things you can do about this: check whether other lenses also show this effect, build a debouncer circuit and put it between x sync output and you trigger input, get a fancier flash trigger as suggested by BenZucker, check whether the hot shoe is switched electronically (if yes it won't bounce and should work better for your task).

 

[Marc B.]

I believe you will find your problem originates with the lens.
Change to another lens, I'll bet your problem won't repeat on another lens.
Sometimes a CLA of the lens will correct, at times, a new shutter or replacement shutter is called for.
Wear within the shutter can cause the flash to fire upon opening, and again when closing.

In your situation though, all bets are off, as you also describe a non-functioning hot shoe.
Time to have your camera body, and the suspect lens CLA'd.

The hot shoe is only an extension of the lens' flash circuit; no different then an extension cord for a table lamp.
If you have a fault in any part of the extension cord, the table lamp won't work.

Because of the bellows focusing, you actually have a built-in extension cord, of sorts, connecting the gold contacts on the face of the movable lens board, to the stationary camera body. This cord, or cable strip, moves in and out, under the bellows-rack/mirror-box, as you focus in or out, (sort of a, rolling-fold).

A couple of the gold contacts, (interfacing lens to body), at the lens mount, carries the closing of the flash circuit, from the lens to the hot shoe, via the cable strip when the lens fires.

Nothing in the camera body influences/triggers the hot shoe, except needing good contacts on the gold pins at the lens board, (lens mount/camera body interface), and a cable strip w/out any breaks/shorts.

 

[raccou]

I have tested this with all my lenses (65, 110 and 180) and they all show this behaviour. One thing I misstated was that it occurs when the flash is connected directly to the lens, that's not true, I was wrong there. So, it's probably not the lenses, but the PW's that are very sensitive...

 

[Rudeofus]

raccou: from your descriptions you sound like you are quite capable of experimenting with electronics: can you try switching a small capacitor between the x sync output and ground? A value around 100nF should do the trick.

 

[haplo602]

this happens on my ETRSi+75PE lens at 4 and 8 second shutter speeds. tested with a cactus v4 trigger that blinks the led on each contact. faster speeds only blink once.

I am suprised to see this on another manufacturer products ... can you test if it happens from a certain shutter speed ?

 

[raccou]

haplo602: It starts at 1/8th of a second and occurs with all slower speeds...

Rudeofus: I'm afraid I don't know anything about electronics