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04-16-2009, 11:32 AM   #1
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Remote Flash Issues

I am trying to use my K10-D with some older remote flash units that I used for a studio lighting setup with my old film cameras. The problem that I'm having is this:

I'm using the pop-up flash as a trigger. I think that the flash is doing it's mini wireless discharge before the shutter opens and it's triggering the slave units on my remote flashes prematurely. Can someone tell me if that is what is happening and if so, what can I do to eliminate the problem?

Is there a possibility that I could use the hot shoe mounted remote flash trigger attached to one of my older flashes to trigger my slaves? Will the shoe mounted remote isolate my K10-D from a possibly too high voltage from the flash that I use as a trigger?

Alternately can I use an older Pentax AF-160 flash in the flash shoe of the K10 without damaging the K10 circuitry. If so will this act a a proper slave trigger for my slaves?

I know that there is a world of knowledge out there in Pentax land, and I'm sure that someone or many someones who could help me.

Thanks in advance for any help you can give me.
Jim

04-16-2009, 11:58 AM   #2
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The on-board flash can't be used to trigger optical slaves. The P-TTL preflash, though weak, is enough to trigger the slave flash(es) prematurely. In addition, you can't adjust the output of the on-board flash.

Like you suggested, a flash attached to the camera's hot shoe can be used to trigger the slaves. This flash should not be in P-TTL mode. The Pentax AF-160 you mentioned can be used for this. The only limitation is that the AF-160 does not have variable output.

My AF-160 has low trigger voltage, about 6V IIRC, but you should measure your unit just to make sure.

The best flash for this purpose is one with variable output, and with the head that can bounce and swivel so you can direct the light.

Edit to add: The preflash strobe from the on-board flash in this case is not for wireless. It is for metering. The camera receives the reflected light, and uses that to command the on-board flash as how much light is sufficient.

Edit again to add: If you use a manual lens (e.g. PK-mount or M42-mount), the on-board flash will fire only one strobe at full power. There will be no P-TTL preflash strobe.

Last edited by SOldBear; 04-16-2009 at 12:08 PM.
04-16-2009, 12:59 PM   #3
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Remote Flash Issues

QuoteOriginally posted by SOldBear Quote
The on-board flash can't be used to trigger optical slaves. The P-TTL preflash, though weak, is enough to trigger the slave flash(es) prematurely. In addition, you can't adjust the output of the on-board flash.

Like you suggested, a flash attached to the camera's hot shoe can be used to trigger the slaves. This flash should not be in P-TTL mode. The Pentax AF-160 you mentioned can be used for this. The only limitation is that the AF-160 does not have variable output.

My AF-160 has low trigger voltage, about 6V IIRC, but you should measure your unit just to make sure.

The best flash for this purpose is one with variable output, and with the head that can bounce and swivel so you can direct the light.

Edit to add: The preflash strobe from the on-board flash in this case is not for wireless. It is for metering. The camera receives the reflected light, and uses that to command the on-board flash as how much light is sufficient.

Edit again to add: If you use a manual lens (e.g. PK-mount or M42-mount), the on-board flash will fire only one strobe at full power. There will be no P-TTL preflash strobe.
Thanks SoldBear you've given me some valuable information. One other question: how do I test the trigger voltage on my AF-160?
Thanks, Jim
04-16-2009, 03:21 PM   #4
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QuoteOriginally posted by jimH Quote
Thanks SoldBear you've given me some valuable information. One other question: how do I test the trigger voltage on my AF-160?
Thanks, Jim
Get out your handy multi-meter (or your neighbour's). Turn on the flash and wait for the ready light to appear. Set the multi-meter to 250v DC just in case - don't want an irate neighbour. Keep reducing the range setting until you can read the reading.

04-16-2009, 03:22 PM   #5
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QuoteOriginally posted by jimH Quote
Thanks SoldBear you've given me some valuable information. One other question: how do I test the trigger voltage on my AF-160?
Thanks, Jim
Get out your handy multi-meter (or your neighbour's). Turn on the flash and wait for the ready light to appear. Set the multi-meter to 250v DC just in case - don't want an irate neighbour. put one wire on the center pin, the other on the casing. Keep reducing the range setting until you can read the reading. Watch for a needle that goes left instead of right. If it does, exchange the two wires from the meter.
04-16-2009, 03:32 PM   #6
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QuoteOriginally posted by Canada_Rockies Quote
Get out your handy multi-meter (or your neighbour's). Turn on the flash and wait for the ready light to appear. Set the multi-meter to 250v DC just in case - don't want an irate neighbour. put one wire on the center pin, the other on the casing. Keep reducing the range setting until you can read the reading. Watch for a needle that goes left instead of right. If it does, exchange the two wires from the meter.
Thanks Canada_Rockies! Man you guys are handy to have around, don't know what I'd do without you. I'm sure glad that I found this forum.
Thanks: Jim
04-16-2009, 04:11 PM   #7
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I've got several questions for all of you folks: Where did you learn all of this information, it surely wasn't from the operating manual.

Another question: I've noticed that I frequently get underexposed shots using the on-board flash. I've even tried to increase the flash exposure by setting the exposure compensation up to + 0.5, +1.0, and decreasing it -05, -1.0, - 1.5, -2.0 with no appreciable affect. What am I doing wrong, and why can't I get properly exposed photographs when using the pop-up flash? I don't think that I'm too far away, because most of these shots are between 6 & 8 feet from the camera. I'm using the kit lens, the 18-55 zoom. When I use the Pentax-M in manual mode with my old flashes I can get some fairly well exposed shots, but I'm having trouble with my kit lens.

Any help here will be appreciated!

Thank you
Jim

Last edited by jimH; 04-16-2009 at 04:28 PM.
04-16-2009, 05:17 PM   #8
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What's your aperture? The more you are stopped down, the shorter the flash range. Same for ISO. Slower shutter speeds have less effect on the flash, but will let more ambient light in.

04-16-2009, 05:51 PM   #9
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QuoteOriginally posted by jimH Quote
I've got several questions for all of you folks: Where did you learn all of this information, it surely wasn't from the operating manual.
<snip> Jim
We got it the same way you are getting it right here. We asked others. The only real advantage we have over you is that we have been doing this for a bit (a lot in my case) longer. The internet makes it easier, but talking with other fotogs is the real way to learn.
04-17-2009, 08:23 AM   #10
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QuoteOriginally posted by Jodokast96 Quote
What's your aperture? The more you are stopped down, the shorter the flash range. Same for ISO. Slower shutter speeds have less effect on the flash, but will let more ambient light in.
I'm using my kit lens 18-55 and shooting in the Program mode, with an ISO setting of 100. I open the aperture wide open and the shots are mostly underexposed and that is shooting in distance range of 8 to 10 feet. I've discovered that if I increase the ISO above 100 those shots at 8 to 10 feet are pretty well exposed. If I increase the ISO to 1600 or even 800 I can get fairly well exposed shots at a distance of 20 feet or more with the on board pop-up flash. I guess that I expected that the ISO would automatically increase with the need for more light, all other settings and limits having been reached. (I've got the auto setting on the ISO to range from 100 to 1600 automatically). Anyone have any thoughts on that issue?

One more thing, I've discovered is if the camera's battery is getting low on charge, it doesn't want to fire my AF-540 when mounted on the camera. Put a fresh battery in the K-10, and then, no problem. I had initially thought that I had fried my circuitry in my K-10 by using my Pentax AF-160 to activate my optical slaves on my studio setup yesterday. So I tried the AF-160 an it fired just fine. Must be that the AF-160 just needs to be triggered and the AF-540 needs a certain level of voltage from the camera to activate it's controls.

Any thoughts or comments are welcome.

Thanks, Jim
07-19-2009, 04:48 AM   #11
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Hi,
I realise this thread is old and you probably don't need any more input, but have you checked the extra "flash exposure compensation" setting in the camera?

BTW, the AF 160 is safe to use on a DSLR, if it is OK. If you ever want to measure another flash, make sure you use a digital voltage meter. Many analogue ones will not give you a correct reading because of too high an internal resistance.
07-20-2009, 12:20 PM   #12
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QuoteOriginally posted by Class A Quote
Hi,
I realise this thread is old and you probably don't need any more input, but have you checked the extra "flash exposure compensation" setting in the camera?

BTW, the AF 160 is safe to use on a DSLR, if it is OK. If you ever want to measure another flash, make sure you use a digital voltage meter. Many analogue ones will not give you a correct reading because of too high an internal resistance.
Thanks for your reply, I can never get too much information when it comes to operating my K10. And thanks also for confirming the AF160 is safe to use on my K10. It will come in handy when using my M lenses especially my f1.4 50mm.

I have since discovered that, although I thought that I had my ISO set on Auto, I didn't but had it set on ISO100. Once I did set it on Auto, with my Auto range from 100-1600 I stopped having problems with under exposure when using my on-board flash. I did check the "flash exposure compensation" under the function menu after reading your post, and it also will help me with my flash range, so long as I don't run out of aperture before I run out of distance. Well, I guess that's why I also have a 540, but I sure like the pop-up for quick flash fill shots.

jimH
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