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06-08-2007, 02:54 AM   #1
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Auto flash with K100D

Hello,

Might be a stupid question, but anyway...
I have a pretty decent auto/manual flash unit National PE-247S. It has worked beautifully on ME Super and other analog SLR's I've tried.
I have tested it with K100D, and the results are very good (certainly better than the built-in flash IMO). I have read somewhere though (and can't remeber where), that due to the quite high discharge voltages on some manual flashes caution should be taken when using them with modern time digital equipment. Is there any truth in this, or is it total woodoo?

Any information, advice, etc. much appreciated.

Thanks,
Bostjan

06-08-2007, 04:29 AM   #2
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It's true. Your flash isn't mentioned on the usual reference but it may be OK as a similar number PE-287S is only 8.3v which is fine with a K100D. Best to measure it yourself though.
Photo Strobe Trigger Voltages
06-08-2007, 05:16 AM   #3
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Do You maybe know the "safe" voltage for K100D? The site You specified, does not individuall specify the voltages for Pentax bodyes....

Thanks,
Bostjan
06-08-2007, 08:00 AM   #4
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I have just measured the voltage accross the pins of my flash unit. It's 237V !!!!!
This is surely waaaay to high!

Bostjan

06-09-2007, 10:03 AM   #5
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237v...check for a decimal point.
06-11-2007, 11:56 AM   #6
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QuoteOriginally posted by Bob Tuttle Quote
237v...check for a decimal point.
Yes, I know it sounds incredible, but it is true. When I prepared for measurement I set my voltmeter to 20V range, waited for flash to fill up, then measured and the scale went to overflow! Then I changed the range to 200V, and it was still to high! I had to switch the range to 1000V to get the measuremet I reported.
I have repeated the measurement three times (i.e. fired the flash in between measurements, then measured). The measurements were consistent. First one 237V, second 228V third 227V (the falling trend probably indicates weakened batteries).

I think that it would be fair from Pentax to state the max switching voltage that their SLR's can take withoput any damage. I tried to find the information in the manual, but were unsucessful. So, one can conclude one of two things:

A.) Pentax feels that the K100D can take all the voltages that any given flash unit can produce

or

B.) They forgot to include this information in the user's manual

Anyhow, I don't think I'll be using my old flash with K100D. Will keep it on my trusty ME Super, and wait for Pentax to come up with a reasonably cheap verion of P-TTL flash... ... or state the information in the future versions of their user manuals (like that's going to happen

Regards,
Bostjan
06-12-2007, 05:16 PM   #7
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I have called Pentax on this a handfull of times to no avail. I was bounced from person to person with never getting an answer beyond: "Let me transfer you to the proper person for that question"

So if anyone finds out this seemingly vital piece of data please post it for the rest of us.
06-12-2007, 08:33 PM   #8
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I spoke with a Pentax (North America) rep about this while troubleshooting an unrelated issue with my K100D.

He said that he himself has tried to get the definitive answer on the safe trigger voltage for Pentax DSLRs from Pentax Japan and it was like talking to a recording. All they would say is "it is safe to use Pentax brand flashes with Pentax DSLRs." Period. Same answer no matter how he rephrased the question.

The rep said that he gave up and got a Wein Safe Sync and now uses 3rd party auto flashes just fine. I did the same: picked up a Sunpak 433 auto and a Wein Safe Sync and am mostly satisfied.

The auto flash does a great job of getting the right exposure indoors (fill flash is hopeless, though, due to the K100D's abysmal flash sync speed). I assume the Safe Sync is doing it's job BUT what an unfortunately constructed device it is!

The Safe Sync sits in the hot shoe via spring clips (no ability to tighten it down) making for a wobbly experience to start with. To make matters much worse the flash receptacle part of the Wein device isn't level (front lip is higher than the sides) so you can't effectively tighten your flash down to it, the tendency is for your flash to want to slip back out of the Wein shoe.

After a few shots while moving around, the flash or Safe Sync needs to be pushed back to the contact or else no flash! A beefy flash like the 433 feels downright precarious on the camera due to the loose fit. Just seems like such a silly oversight for an otherwise decent product.

Someday I'll get a voltmeter and test my 433. If it consistently measures around 8V or less, I'm ditching the Wein Safe Sync!

06-13-2007, 01:44 PM   #9
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Since past last days, I have been thinking of building something simmilar to the Wein Safe Sync myself, but I was thinking of building it inside flash housing... What would be needed is some kind of optocoupler circuit to isolate the hotshoe on camera from flash. The power can be taken from batteries inside flash.

Anyway, if there is somebody out there that can tell us the safe voltages that can be used on K1xxD cameras, I'd be really interested


Regards,
Bostjan

Last edited by Bostjan; 06-13-2007 at 11:43 PM.
06-13-2007, 05:35 PM   #10
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Great idea. If you have the ability to choose the voltage, as you do, set it for 6v. Really, the ISO specs say that compliant cameras should take up to 24v (and I'm sure the K100D is compliant) but 6v seems to be what most people shoot for to be safe with all cameras. 6v is what the Wein Safe Sync uses.
12-03-2008, 07:42 PM   #11
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QuoteOriginally posted by Bostjan Quote
I have just measured the voltage accross the pins of my flash unit. It's 237V !!!!!
And how many times did your K100D survive that?
It'll be impressive if it did only once.
12-04-2008, 01:40 AM   #12
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QuoteOriginally posted by Class A Quote
And how many times did your K100D survive that?
It'll be impressive if it did only once.
:-) it survived... more than one time, I believe it was about 10 or 15 shots, before I got suspicious and started the thread. After I measured the voltage, I have never again used it on my K100D. But I use it regularly on my ME Super.

Bostjan
12-04-2008, 02:54 PM   #13
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QuoteOriginally posted by Bostjan Quote
:-) it survived... more than one time, I believe it was about 10 or 15 shots, before I got suspicious and started the thread.
It did well, didn't it? You should stick a kind of medal on it.

QuoteOriginally posted by Bostjan Quote
After I measured the voltage, I have never again used it on my K100D.
That's very likely a very good idea. Anything over 30V would be totally out of the question, I'd say, and the safe voltage may actually be a lot lower still. I'm trying to find out with this poll.
12-05-2008, 04:55 AM   #14
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A very timely thread update - I just pulled out my old Nissin 340T (GN 34 vs the GN13 on my K200D) to use again. According to the Trigger Voltage link
I've got 190V. The site also tells you how to measure your own voltage BTW

In the meantime, the 340T has gone back into the cupboard! Might drag out my flash sync photodiode......
12-05-2008, 05:52 AM   #15
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Well, you know, there are voltage regulating hotshe adapters available.

I believe one of them is called a "Safesync" or something like that.
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