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03-30-2008, 10:20 AM   #1
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Flash firing immediately on "2s delay" drive mode

Hello folks;

While a old manual-focus lens (Cosina) attached to my K100D Super on "2 secs self-timer" Drive Mode, everything is fine, i.e. the mirror goes up, 2 seconds delay, then the shutter opens with the flash firing.

However, when I attach the kit lens (18-55) the very same camera on the very same Drive Mode fires the flash when I press the shutter AND when the shutter is released (After the 2 second delay). Though this may not seem to be a big problem, it unfortunately causes my 25-year old servo flash to fire prematurely (i.e. 2 seconds before the actual photograph is taken). I tried the manual focus mode when the 18-55 is attached but this problem still continues.

Any comments for this?

Thanks in advance

03-30-2008, 10:23 AM   #2
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QuoteOriginally posted by oguzgel Quote
Hello folks;

While a old manual-focus lens (Cosina) attached to my K100D Super on "2 secs self-timer" Drive Mode, everything is fine, i.e. the mirror goes up, 2 seconds delay, then the shutter opens with the flash firing.

However, when I attach the kit lens (18-55) the very same camera on the very same Drive Mode fires the flash when I press the shutter AND when the shutter is released (After the 2 second delay). Though this may not seem to be a big problem, it unfortunately causes my 25-year old servo flash to fire prematurely (i.e. 2 seconds before the actual photograph is taken). I tried the manual focus mode when the 18-55 is attached but this problem still continues.

Any comments for this?

Thanks in advance
it's probably because of the preflash PTTL that's used to determine correct flash exposure. does it on my k110d, as well.
03-30-2008, 10:31 AM   #3
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Thanks for prompt reply, OniFactor

Hmm... So should I understand it like this?

"Although the camera is on manual mode and I set the aperture and shutterspeed manually, it will always check for correct exposure when I manually pop the flash up. And therefore, the consequence for this will be the premature firing of the flash."

If this is correct, than, there is almost nothing else to do, right?
03-30-2008, 10:39 AM   #4
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QuoteOriginally posted by oguzgel Quote
Thanks for prompt reply, OniFactor

Hmm... So should I understand it like this?

"Although the camera is on manual mode and I set the aperture and shutterspeed manually, it will always check for correct exposure when I manually pop the flash up. And therefore, the consequence for this will be the premature firing of the flash."

If this is correct, than, there is almost nothing else to do, right?
kind of. there is no manual setting for the onboard flash, you can only do flash compensation. the way it figures out how much flash to use is this:

when you hit the shutter button, before anything at all happens, it fires off the preflash signal, which is a certain percentage of the flash's capability. the metering sensors meter off that preflash, and determine how much flash is required for a proper exposure, taking into account the flash exposure compensation., and then the actual picture is taken.

the only real way around this, is to use an older M type lens, or to use an external flash, attached to the hotshoe

03-30-2008, 01:00 PM   #5
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Unfortunately there's not much you can do with the equipment you are using.... Newer slave flashes have a switch that enables the flash to ignore pre-flashes and will only trigger on the second flash that it "sees".

There is a work around though... get a cheap radio slave (around $20) and use that to trigger your off-camera slave and because the radio slave does not use PTTL, your flash should be able to work the way you want. An example of the radio trigger is here...



The information for this radio slave can be found here:

4 Channels Wireless Flash Trigger Digital Radio Slave - eBay (item 260225329689 end time Apr-04-08 05:34:24 PDT)

The particular model shown above can be used either with a studio strobe or on a tripod with a standard external camera flash which I believe is what you are using... I use one just like it and it works just great in manual mode. It does not support PTTL.

Alex
03-30-2008, 01:20 PM   #6
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Thanks, guys. Your replies helped a lot. A very effective forum that I have joined a couple of hours ago and found both correct and useful answers!... Hope I will contribute more in the future.
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