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01-10-2012, 02:31 PM   #1
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Wireless PTTL with on board flash

Hi I just bought a wireless PTTL flash (Cactus AF50). I figured out quite easily how to get it to fire wirelessly using the built in pop up flash.
My question is I don't like that the image now has 2 light source (the pop up and the wireless flash). Is there a way to have the pop up flash to prefire to signal the wireless flash and then take the image ? Or this is just how wireless PTTL works ?

Thanks

01-10-2012, 02:45 PM   #2
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In p-TTL wireless, there is no way to prevent the control/master flash (in this case, the built-in flash) from firing during exposure.

In control mode, the built-in flash fires with reduced power (compared to master mode), but it fires nonetheless.
01-10-2012, 02:53 PM   #3
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I see, so the only way to use the flash wirelessly with only 1 light source is via RF / cable ?
There is an option in custom menu "flash in wireless mode" I set it to off which didn't make any difference, anyone know what does this option do exactly ?
01-10-2012, 02:59 PM   #4
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QuoteOriginally posted by Azzy Quote
I see, so the only way to use the flash wirelessly with only 1 light source is via RF / cable ?
Yes.

QuoteOriginally posted by Azzy Quote
There is an option in custom menu "flash in wireless mode" I set it to off which didn't make any difference, anyone know what does this option do exactly ?
Off : control mode (firing with reduced power)
On: master mode

You may also want to partially cover the control (built-in) flash. The best material is a piece of developed exposed film (ask your local photo printing shop if you have one local). But that of course will reduce the range.

01-10-2012, 03:02 PM   #5
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Try using an elastic band to hold a small, white card in front of the pop-up flash. This will direct the light up and soften the effect on the picture but should still be enough to trigger the other flash if you're indoors.
01-10-2012, 03:13 PM   #6
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The wireless flash is an optical feature that uses the light from the master/control to communicate with the slave flash. As long as the master/control flash has enough light to direct itself to the sensor of the slave it should trigger the slave every time. A more effective setup incorporates another external P-TTL flash with tilt and swivel head so that the master/control flash can point itself straight at the slave.
01-10-2012, 03:21 PM   #7
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QuoteOriginally posted by Azzy Quote
I see, so the only way to use the flash wirelessly with only 1 light source is via RF / cable ?
That is correct.

The only way your wireless flash will know when to fire, both for pre-flash to measure the exposure, and for the actual exposure, is when the on-board flash tells it to do so.

If in control mode, the on-board is used just for signaling so it fires in a reduced power that should not affect much the exposure.
01-10-2012, 03:32 PM   #8
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QuoteOriginally posted by Ash Quote
The wireless flash is an optical feature that uses the light from the master/control to communicate with the slave flash. As long as the master/control flash has enough light to direct itself to the sensor of the slave it should trigger the slave every time. A more effective setup incorporates another external P-TTL flash with tilt and swivel head so that the master/control flash can point itself straight at the slave.

I'm aware of this, I was just wondering if there is a way to pre-fire the onboard flash to ready tje slave so there is only 1 light source.

Another swivel external flash is a good idea, would it still trigger the slave if the light is bounced to reach the slave ?

01-10-2012, 03:54 PM   #9
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QuoteOriginally posted by Azzy Quote
I was just wondering if there is a way to pre-fire the onboard flash to ready tje slave so there is only 1 light source
No but the popup flash will have a negligible lighting effect on the exposure when set as the control.

QuoteOriginally posted by Azzy Quote
Another swivel external flash is a good idea, would it still trigger the slave if the light is bounced to reach the slave ?
Yes, as long as there's enough light to get to the slave's sensor. I'd suggest just pointing the head of the control flash directly to the slave's sensor, since you're not likely wanting a bounced flash to contribute to your final exposure (you've already set up a better controlled light source in the slave - if you want two light sources, you may as well set the two flashes up as slaves wirelessly triggered by the popup.)
01-11-2012, 06:56 AM   #10
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If you set the builtin flash to controller then it only flahes the pre-flash (when the shutter is closed) so the flash won't effect exposure at all.
01-11-2012, 07:55 AM   #11
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L33tGreg : you're wrong, even in Controller mode, the on-board flash will fire during the exposure, albeit at a reduced power, as mentioned above.
On previous models, it worked fine, but on the K5 and K7, this "reduced" power is way too powerful, and can still have a big impact if you are using big apertures and/or high iso...

I personally use a Nikon SG-3IR flash screen to block the on-board flash when needed.
01-11-2012, 09:17 AM   #12
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QuoteOriginally posted by L33tGreg Quote
If you set the builtin flash to controller then it only flahes the pre-flash (when the shutter is closed) so the flash won't effect exposure at all.
Don't take anyone's word for it.

Take a photo with the built-in flash visible in a mirror and prove/disprove it yourself.
01-11-2012, 09:36 AM   #13
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QuoteOriginally posted by SOldBear Quote
Don't take anyone's word for it.

Take a photo with the built-in flash visible in a mirror and prove/disprove it yourself.

Even better, use the 2 sec timer. You will see a pre flash the moment you press the shutter and the actual flash 2 seconds later.
01-11-2012, 03:51 PM   #14
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QuoteOriginally posted by demp10 Quote
Even better, use the 2 sec timer. You will see a pre flash the moment you press the shutter and the actual flash 2 seconds later.
thanks will check this out
01-11-2012, 06:18 PM   #15
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QuoteOriginally posted by SOldBear Quote
Don't take anyone's word for it.

Take a photo with the built-in flash visible in a mirror and prove/disprove it yourself.
I think you're miss reading it he says "so the flash won't effect exposure at all." that's something else then not firing.
If you're shooting at a what longer distance the little controller flash is indeed so little it will so good as nothing effect the exposure indeed, the closer you stand to your subject the more the controller flash becomes visible but in most cases that isn't a problem either.
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