X Sync Flash problem


Pencanon

Link Posted 07/03/2010 - 16:09
I have a unbrella mains flash that plugs into the X Sync socket on my Pentax K7 and Canon 5DMkII. Whilst photographing my canon works perfectly with the flash and recharges mains flash each time I press the shutter. The K7 with updated firmware fires the flash but fails to flash again unless I turn off the flash unit and switch on again. I have tried the camera using different modes but it still has the same problem. Its not a failure with the canon so assume the K7 has a fault or Pentax hasn't thought about this. Anybody else had the problem, if so is their a solution

JohnX

Link Posted 07/03/2010 - 16:17
There was a recent thread on this Forum that dealt with something very like the situation you describe. Suggest you search posts dated 2010.

I remember one of the Forum members who responded was MattMatic.

From memory it's something to do with the way Pentax flash circuits are protected/triggered.

Pencanon

Link Posted 07/03/2010 - 16:29
Thanks searched and found the thread. Seems there no solution to x sync firing the flash again after 1st shutter release. So pleased I have an alternative camera make. Hope pentax can remedy this problem with the K7 and I believe 10D, 20D otherwise anyone taking studio shots may as well get a nikon, canon or an olympus

Anvh

Link Posted 07/03/2010 - 16:40
Maybe this is your answer.

Quote:
It really was the cable. But it was not what you thought - the cable was OK, only the polarity has been reversed!

If your Pentax K7 does not want to fire a flash with x-sync cable connection, check the polarity! The pinout of the x-sync cable is as follows: the outer shield of the x-sync (-) should be connected to a part of the mini-jack that is the closest to the cable which can also be connected to the mini-jack's outer shield. The middle prong (+) of the x-sync must be connected to the very tip of the jack.

When checking, connect the flash with the cable using the mini-jack end, leaving the x-sync connector unconnected (the camera is not needed!). Take the volt meter and connect ground (also called (-)) to the outer shield of x-sync connector and touch the middle prong with the (+) connector. Turn the flash on and take the reading. It should be +something volts (if this "something" is too large - do not connect as you can possibly fry your camera). If your meter reads minus "something" volts you must reverse the polarity by unscrewing the mini-jack and re-soldering the wires.

This setting has worked for me. I must add that after correcting polarity my K7 works flawlessly, firing the external flash as necessary despite the flash being wrongly connected for a few shots.

This shows that K7 is very well designed and can cope (to some extent) with even the most serious of user errors.


Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

JohnX

Link Posted 07/03/2010 - 17:39
I thought there was a proposed solution?

Could have been more than one thread.

allbend

Link Posted 07/03/2010 - 19:13
I have no problem firing my studio flash units repetedly from the X sync socket of my K20D

allan
K20D/DBG2 | Pentax DA 18-55/3.5-5.6 AL| Tamron DiAF 70-300/4-5.6 | Pentax A 28/2.8 | Tamron ad2P/KA 28-70/3.5-4.6 | Tamron ad2P/KA SP90/2.5 +macro 1.1-1.2 extn | Teleplus KAX 2x | Vivitar PK 2x22 |Metz 58AF1 Flash| Canon FD Bodies: T90; T70 | FD Lenses C50/1.8; Vivitar S1 70-200/3.5; Sigma 400/5.6; Vivitar AT4 ext tubes; CFD 2xA extender; Tamron ad2CFD 28-70/3.5-4.5 | Cullman CX35 + offshoe cables |

Pencanon

Link Posted 08/03/2010 - 12:19
Thanks for solution. I need to get another flash lead then reverse the polarity as described above. As Anvh has safely used it this way I assume this won't damage my camera or flash? Its a calumet genesis unit I use, maybe other off camera flash units work ok with the K7.

MattMatic

Link Posted 08/03/2010 - 14:03
There's another thread about this...

Technical reasons appear to be:
* Canon uses transistor trigger
* Pentax uses thyristor trigger
* Flash unit takes more than 2mA to trigger - thus holding the Pentax's thyristor switched on.

Canon is not very well protected, but the Pentax is. The Calumet lights are 5V, but obviously are taking a little more current than they need (you could trigger on much less than 1mA - which would be fine with the thyristor).

I've toyed with the idea of making a little interface to do the job. You may find that a Wein Safe-Sync (IIRC) will also work.

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

Anvh

Link Posted 08/03/2010 - 15:17
Pencanon wrote:
Thanks for solution. I need to get another flash lead then reverse the polarity as described above. As Anvh has safely used it this way I assume this won't damage my camera or flash? Its a calumet genesis unit I use, maybe other off camera flash units work ok with the K7.

No I haven't safely use it that way, it was quoted from DPreview.
Someone had the same problem as you and, the answer was that the Cable is the first one to fail and then when this was the response on that.

You should check the polarity of you flash and and the camera then you know if that's the problem or not, do not assume I've it right.
Everything is at your own risk
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

gartmore

Link Posted 08/03/2010 - 15:35
Pencanon wrote:
Thanks searched and found the thread. Seems there no solution to x sync firing the flash again after 1st shutter release. So pleased I have an alternative camera make. Hope pentax can remedy this problem with the K7 and I believe 10D, 20D otherwise anyone taking studio shots may as well get a nikon, canon or an olympus

Most people taking studio shots in this day and age use wireless triggers Much more convenient, cheap and no cables to trip over.
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -

Anvh

Link Posted 08/03/2010 - 15:51
Ken is right, for the price I can recommend the Cactus V4, they are not pro quality though. The good thing is they come with the cable you need so no need to buy that separately. Pcoketwizard are almost charging as much for the cable as what the Cactus V4 cost

link
There are of course also more professional solutions. link
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
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