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Re: [OM] fill flash - am I missing something?

Subject: Re: [OM] fill flash - am I missing something?
From: suchismit@xxxxxxxxx
Date: Tue, 05 Nov 2002 19:44:47 +0000
Wayne,
you are right. In AUTO mode the shutter will fire
at 1/60, no-matter-what-the-finder-says. The finder
info merely gives you an idea of what the ambient
light shutter speed should be proper exposure, if there 
was no flash.

I will try to guess why he says to set shutter speed
at 1/30 or slower in manual. In a camera in good working 
condition the shutter curtains would be completely open
at 1/60s, so 1/60 should be ok for manual flash. But
with usage the shutter may not actually fire at 1/60
when the dial is set to 1/60, and there is the possibity 
that the curtains may not be fully open. However unless 
unless there is something terribly wrong with the camera 
1/30 or slower is a safe bet. Again, thats only my guess,
there could be other reasons too.

-Tim


> 
> > > Another question then, if the flash sync speed is 1/60 ttl, why does
> Carl
> > > Shipman in his book say to "set shutter speed to1/30 or slower" when
> using
> > > manual operation or normal auto operation (page 97, 98, 10th edition)?
> Is
> > he
> > > just trying to be extra careful? Is there some circumstance where they
> > don't
> > > sync at 1/60 manual and 1/60 mechanical?
> > > Wayne
> 
> 
> 
> > Wayne ... what I think Shipman is saying by setting the shutter speed to
> > 1/30 or slower is to allow for more ambient light to reach the film. >
> > John H
> 
> Well maybe, but I went back and read it again, and it seems to me he is just
> describing how it works. I can't see that he's talking about balancing
> ambient and flash in that section. I think he made a mistake. If not a
> mistake or typo, then while the theoretical sync speed is 1/60 in manual or
> mechanical mode on the 2s,  the actual and practical sync speed is 1/30.
> 
> On page 92, talking about ttl,  he writes, "the theoretical X-sync speed for
> OM cameras is 1/60 second but there are practical considerations that
> sometimes suggest using 1/30. This applies with a flash on TTL automatic."
> He goes on to explain, as we know, that if the ambient light requires a
> faster shutter speed, the flash won't fire.  So let's say the ambient
> requires 1/70, then the flash will not fire. We would be fooled becuase we
> saw 1/60 in the finder, thought it would fire, and got fooled because the
> viewfinder doesn't display 1/70. So by setting to 1/30, we know it will fire
> for sure. Albeit it fires at 1/60, PERIOD, as Tim says. So we need to adjust
> until we see 1/30 in the viewfinder, which means if we're in auto mode, we
> get an aperture setting for 1/30 ambient light, but it still really fires at
> 1/60 because that is what the flash tells it to do. (Forget program mode, we
> never know for sure what its going to do there) So the ambient is actually
> reduced even more than needed by the smaller aperture required to get the
> viewfinder reading down to 1/30, while it actually fires at 1/60. Using ttl
> then makes it harder to balance ambient and flash, as you'll normally have
> to remember you'll be at least one aperture/stop under for ambient.
> 
> However, what I asked was, why does he say to set it to 1/30 or slower when
> using flash in "normal auto operation" or "manual operation". His
> instructions, repeated twice (pgs. 97,98) are "Set the camera to manual.....
> Set shutter speed to 1/30 or slower". Going back to his statement above
> taken from page 92, I can't see why the thoeretical sync speed applies when
> setting the shutter speed manually, as he seems to make it. And if we're not
> setting the shutter speed manually, there is no sense of talking
> theorietical sync speed anyways, because it fires at 1/60 Period, according
> to Tim. The shutter speed isn't actually changed, only the number in the
> viewfinder is changed.
> 
> Maybe I am more confused, but right now I'm assuming (hoping) he made a
> mistake, because I've been using the rule of 1/60 or slower, not 1/30 or
> slower, when the camera is set to manual shutter speed.
> 
> Wayne (still open to learn if someone can get it through my thick head)
> 
> 
> 
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