Old question - but one that still needs an answer
Obviously the safest option is to use an adaptor like that linked to by John.
Dan
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....
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
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.
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.
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.
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
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
(For gallery, tips and links)
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.
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
(For gallery, tips and links)
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.
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.
Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
Add Comment
To leave a comment - Log in to Pentax User or create a new account.
120 posts
14 years
Norfolk
(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.
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