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Old Jun 26, 2013, 2:10 PM   #1
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Default 2nd curtain question

Trying to learn more about second curtain.my understanding was that it fired at the end of the shot. I was playing with bulb mode to see if it does fire at the end. Held shutter open a few seconds and when I released the shutter it did fire but the flash also fired at the beginning so the flash actually fired twice. What am I missing? Thanks
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Old Jun 26, 2013, 4:44 PM   #2
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G'day mate

My understanding is that all flash systems [in-camera eTTL + external TTL] will flash multiple times - I have seen it many times in workshops etc

The first flash is a pre-flash to determine final exposure;
often the 2nd flash is the anti-red eye flash, and
the 3rd & final flash is the actual exposure

As the shutter does not fire until the final flash, the previous flashes are not recorded

I cannot comment regarding the use of Bulb - you can help us all out with this one though ... Q: when on bulb let the pre-flash go off, cover the lens momentarily and fire the shutter to force the main flash ... does anything show on the image from the pre flash??

Phil
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Old Jun 27, 2013, 4:59 PM   #3
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Phil's comment is likely correct. I have never tried using auto flash with bulb mode - didn't expect it to work.
IIRC, the pre-flash for metering occurs before the shutter opens, so it should not affect the final exposure. If the shutter is open too long in bulb, the additional light from the trailing curtain flash could cause the final result to be overexposed, though.

brian
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Old Jun 28, 2013, 3:40 AM   #4
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You may find that the initial flash was for pre-focusing,if you were in poor light...?
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