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Old question - but one that still needs an answer

Telstar
Posted 22/02/2010 - 10:33 Link
Apologies for bringing this up again, but the sticky question of safe trigger voltages is a personal concern at the mo, and although there have been a few threads here and elsewhere about it I dont think a definite answer has ever been agreed.

(Whether this is possible without PENTAX themselves stating in black and white what is safe is of course debatable but...)

Ive recently picked up an old Sunpak GX8R ringflash. Now this would be absolutely perfect on my dental 100 macro, but of course there is the trigger voltage issues.

The last 'definite' answer I can find on this is that to be 100% safe with no worries 10v is the over-cautious answer, and a couple of differing sources on this and other forums claim that pentax themselves have stated 30v

Now I somewhat bravely/stupidly connected and used the ringflash on my GX20 - with no probs whatsoever, though it was set on 1/4 power for this test. (this is through the pc connection on the side, as it has no hotshoe being a ringflash unit)

I now have been able to use a decent voltmeter on it this morning at work, and have the following results

1/4 power setting - 24v
1/2 power setting - 30v
full power setting 42v

the question is do i risk it again - on the lower settings? the 6-7 shots i took on 1/4 power had no effect on my body, but was i just lucky....?

Obviously i'm never gonna use it on full power..


If not is there any handy 'interface' units that will plug in between it and my pc connection to ensure by body remains safe?


Cheers Tel.
Bodies: GX20 | MZ-3 | MZ-M | Auto 110 complete kit
Primes: DA*300 F4 | DA40 F2.8 Ltd. | SMC-A 50/1.7 | Sigma 30mm F1.4 | Sirius 28/2.8
Macro : SMC-A Dental 100 macro
Zooms: 12-24 SA | 18-55 SA | 50-200 SA | 28-80 FA | 35-80 F | Vivitar 28-200
Other: Bellows | Tube sets | Vivitar 2x PK/A Tele | SEF-36PZF Flash | SBG-D1V Grip | Billingham 335


My Flickr
JohnX
Posted 22/02/2010 - 10:40 Link
Can't answer all your questions, but look here for an adapter that protects from high trigger voltages. link
Daniel Bridge
Posted 22/02/2010 - 11:13 Link
I use a Centon FG-30 on my K10D. According to this site, its trigger voltage is around 200V, although I've not tested it to confirm. My camera's fine, as is my *istD I used before it, and I've had two different copies of this flash. I may just be lucky though...

Obviously the safest option is to use an adaptor like that linked to by John.

Dan
K-3, a macro lens and a DA*300mm...
Telstar
Posted 22/02/2010 - 11:23 Link
Thanks guys. been doing a little more research, and in a thread on pentaxforums
www.pentaxforums.com/forums/camera-studio-accessories/87679-flash-trigger-voltag...
someone there clearly states that the K20d (i.e. the same as my GX20) does have a protection circuit built in for the Pc socket. The problem is that this doesnt include the hotshoe, and hence a number of K10's and K20's have had circuits burnt out from using 200+V flashes on the shoe. looks like i'll be fine using this on the pc connection then....
Bodies: GX20 | MZ-3 | MZ-M | Auto 110 complete kit
Primes: DA*300 F4 | DA40 F2.8 Ltd. | SMC-A 50/1.7 | Sigma 30mm F1.4 | Sirius 28/2.8
Macro : SMC-A Dental 100 macro
Zooms: 12-24 SA | 18-55 SA | 50-200 SA | 28-80 FA | 35-80 F | Vivitar 28-200
Other: Bellows | Tube sets | Vivitar 2x PK/A Tele | SEF-36PZF Flash | SBG-D1V Grip | Billingham 335


My Flickr
Anvh
Posted 22/02/2010 - 11:30 Link
Form what I understand the hot shoe can handle 200volt as well.
If you're 100% sure with the PC socket and want to use that there are of course adapters.
Most have a hotshoe fitting so you can place them on your camera as normal or because it works by a cord you can be more creative.
Stefan
Comment Image

K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
greyhoundman
Posted 22/02/2010 - 12:54 Link
The safety circuit for the PC connector does not extend to the hotshoe.

If Pentax is ISO compliant, the top voltage on the hotshoe would be 24 volts. They don't claim to be ISO compliant.

The over voltage does not always cause instant damage. But the continued spikes can suddenly blow out circuit boards.
Telstar
Posted 22/02/2010 - 15:00 Link
Minor update, had a bit more time on my hands this afternoon so got my hands on a proper (£200) digital meter, rather than the cheap-ish £30 one in my toolkit.

Forget my earlier figures, the GX8R measures 201V on whatever setting (1/4,1/2 or full). If I hadnt discovered the pc port circuit protection i'd be rather worried!

Just shows to take supposed 'measured' figures for old flashes with a pinch of salt, without the correct equipment so-called readings can be dangerously misleading.
Bodies: GX20 | MZ-3 | MZ-M | Auto 110 complete kit
Primes: DA*300 F4 | DA40 F2.8 Ltd. | SMC-A 50/1.7 | Sigma 30mm F1.4 | Sirius 28/2.8
Macro : SMC-A Dental 100 macro
Zooms: 12-24 SA | 18-55 SA | 50-200 SA | 28-80 FA | 35-80 F | Vivitar 28-200
Other: Bellows | Tube sets | Vivitar 2x PK/A Tele | SEF-36PZF Flash | SBG-D1V Grip | Billingham 335


My Flickr
MattMatic
Posted 22/02/2010 - 16:33 Link
Sounds like your £30 meter needs a visit to the recycling

I'd be surprised if the trigger voltage changed with flash power - after all, the reduced flash power is just partially discharging the capacitor. The cap is fully charged whatever the flash power is set to So your digital meter is correct.

I'm surprised at the comments about only the PC being protected... from tests earlier, it appears that both the hotshoe AND PC socket have thyristors on them. We were testing for 'lockups' when more than 2mA goes through the flash trigger (as in some studio lights) which lock the thyristors on (until power is removed).

Other comments (even from Pentax) say 300V (which is the smallest max voltage for a thyristor). I've seen other comments saying 30V... but to be honest, I have not actually heard of any Pentax being fried

I've heard of Canons being fried though They appear to have a transistor output on the flash circuit (which doesn't lock up with the studio lights, but will get fried with old flash guns).


I think Clarky has used high trigger voltages without any problems....

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
greyhoundman
Posted 22/02/2010 - 17:08 Link
When I asked a Pentax tech, he said only PC socket was protected from high voltage.
Plus their own video only states the PC socket is protected.
http://www.youtube.com/watch?v=fZlVEe2y9e4

And I know of a K10D and two K20D's fried from using old Vivitar 283's.
MattMatic
Posted 22/02/2010 - 17:17 Link
Quote:
And I know of a K10D and two K20D's fried from using old Vivitar 283's.

I stand corrected

Just see the end of the video - the PC is definitely protected, but the jury is probably out on the hotshoe. It may have been that older Pentax DSLRs had protection on both (like the *ist-D) (But it's still true that the K20D hotshoe is behaving like a thyristor...)

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
Edited by MattMatic: 22/02/2010 - 17:24
greyhoundman
Posted 22/02/2010 - 17:24 Link
I'm not wanting to argue. Just help folks from "bricking" a great camera.
Since I had to repair my first DS, I've taken an interest in the internals of the digital cameras. Their circuit boards seem to be a tad fragile in certain circumstances.
Dangermouse
Posted 15/09/2010 - 23:26 Link
Does anyone know what trigger voltage the current digital flashes output? That would be an obvious way to answer the question once and for all.

Pentax have never said that you can't use their own older flashes IIRC, and the AF240Z has a trigger voltage of between 7-8v. I therefore take that as my max safe voltage, as I have an AF240Z for compact on-camera external flash and a Metz 45CL-1 (6-7v) as the hammerhead monster.
Matt

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
pentaxian450
Posted 16/09/2010 - 00:15 Link
If you use the flash with the PC sync, DON'T PUT IT ON THE HOT SHOE. The voltage would travel through both the PC sync and the hot shoe, so you could still potentially fry some electronics in the camera.
Yves (another one of those crazy Canucks)

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