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Old Jan 21, 2006, 5:41 AM   #1
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Hi,

Is there anyway to change the flash timing to be either like a fill flash, or a pre flash or a delayed flash.

I also have a S70 and i can take some decent pictures hand held in very low or artificial light capturing most of the back ground details too by means of flash timing.

Is there a setting similar to the one in S70.



And is there anyways to play around with flash timing when it comes to macro mode.



thanks

SVB
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Old Jan 21, 2006, 9:48 AM   #2
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I'm not entirely sure I understand your 'timing' vs. 'exposure' statement, but I'll take a cut. As for 'timing' the 20d allows for either first curtain or second curtain synch via custom functions. But that mode doesn't affect exposure at all. What it will affect is where you see any 'motion' in your photo. In first curtain synch, you may still see some motion going 'away' from the subject as the subject moves after the flash fires. 2nd curtain synch allows you to delay the flash fire until the shutter is about to close - that way any motion blur is leading up to the subject.

How much background is exposed, or whether or not the flash is operating as fill has nothing to do with WHEN the flash fires. It has to do with how the shot is metered. If you allow the camera to determine exposure for ambient light - say by using Av or Tv mode (which means long shutter speeds) the flash will use less output and the long shutter speed/wide aperture will expose more of the background. If you use manual or P or auto, and use a faster shutter/narrow aperture the flash will compensate to put out more power and try to properly expose your subject leaving the background dark. Realize, however, the built in flash is not that powerful and doesn't have much of a reach so you may get underexposed shots if your subject is more than 10' away.

So, if you want more background in detail, use a slow shutter speed - whatever you can safely handhold (1/60 or 1/30), set the aperture to the widest value and bump up your ISO to say 400. This will expose for more ambient light and more background will be visible.
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Old Jan 21, 2006, 10:14 AM   #3
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nymphetamine wrote:
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And is there anyways to play around with flash timing when it comes to macro mode.
JohnG is correct

There's a mode which works very well with flash, especially macro, but most folks are afraid to use: The MANUAL mode on the camera (the flash will still be in automatic)

Try it - switch your camera to the manual mode and as you vary the shutter/aperture the pointer -2..-1..v..+1..+2 in the viewfinder indicates the exposure value to capture the background detail as much as you want - When you hit the shutter release the flash will correctly (automatically) fill in the foreground!
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Old Jan 21, 2006, 3:42 PM   #4
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i was trying to shoot in the macro mode and i wanted the flash to fire a fraction before the actual shutter release. There is a function in my canon S70 which says =/- flash with correction from -2 t0 +2 and this actually flashes based on the shutter release. If its 0 the flash fires as the shutter opens and -2 fires a fraction before the shutter release and +2 fires a fraction after the shutter releases.



i wanted to know if something like this can be achieved.

Hope this time i am stating it correctly.



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Old Jan 21, 2006, 9:56 PM   #5
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nymphetamine wrote:
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There is a function in my canon S70 which says =/- flash with correction from -2 t0 +2 and this actually flashes based on the shutter release. If its 0 the flash fires as the shutter opens and -2 fires a fraction before the shutter release and +2 fires a fraction after the shutter releases.
It's the same on the Canon!

This function does not fire before (or after) the shutter release. It's called flash exposure compensation (FEC) and is availbale on the camera as well as the external mounted flash :idea:
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