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In this chapter we'll be looking at the
relationship
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of shutter speeds and apertures to
flash.
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Now there are four segments that I'm
going to break this chapter into.
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The first one is understanding
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flash
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sync speeds.
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The second one is understanding the
relationship of ambient light that's
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existing light to our flash, and how we
can control that with shutter speeds.
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The third
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segment is going to be
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understanding the relationship of
apertures to flash, which basically
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control the amount of light coming in,
the amount of flashlight coming in, and
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how the distance of the flash away can
also change the power of the flash, and
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obviously changing the power of the
flash itself.
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And then the 4th section will be
understanding first curtain and second
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curtain synchronization.
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So let's start off with understanding
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flash sync speeds.
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This is something that confuses
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a lot of people, and I understand why
it confuses a lot of people.
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The simple explanation is that
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cameras have a set
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flash sync speed listed.
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Some cameras it might be 125th
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of a second, shutter speed, some
cameras it might be 200th of a second.
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But people don't really understand why
there is a set flash sync speed and
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what that actually means.
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And then more recently, we've had
developments with high speed sync as
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well, which has confused things
further.
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So I'm going to explain
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both of those things.
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Now.
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First of all, to understand flash sink
speeds, we need to understand how the
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shutter works.
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So let's take a look at this old film
camera.
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This is one of my favorite cameras.
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Actually, I used to use.
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One of these is the cannon f one.
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And if I'm just going to open this up
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here, we can see the shutter.
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This is the focal plane shutter.
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And what I'm going to do let's just
wind to the camera.
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This used to be for film.
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You'll see the shutter
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open and closed.
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There let's just have another look at
that.
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There's the shutter
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opening and closing.
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Ok.
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Now, I
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showed you on a film camera, because
obviously we can see all the way
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through it.
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Let's have a look on a digital camera,
like this, five d, mark, three.
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If I take the lens off,
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and you can see, there's the mirror in
the way,
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open the shutter,
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and you should be able to see the green
colored
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ccd or seamos sensor at the back of the
camera.
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And just see if I can tilt it to the
light to get you to
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not sure which angle you might be able
to pick that up, just if you can see
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that sensor in there.
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And there's the shutter
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opening and closing, where the mirror
is lifting up, and then the shutter is
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opening and closing.
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Now,
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the difficult thing for most people to
understand
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is that
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if the flash duration
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is very fast, and we know we've already
covered flash durations,
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we know that the flash duration might be
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500th of a second or a 1000th of a
second, 2000th of a second.
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So if the flash duration is that fast,
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then why can't that flash duration be
incorporated
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into a shutter speed, which is longer?
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So for example, why can't we get a
2000th of a second flash duration
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inside a 1000th of a second shot speed?
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And that's a very good question.
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Why are we limited to shutter sync
speeds of 125th
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of a second or 200th of a second, when
the flash duration is actually much,
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much faster and should be able to fit
within that shutter speed?
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Well, there's a good reason.
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Let's explain exactly how these focal
plane shutters are working.
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First of all,
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so let's imagine that this green card
is a sensor in the camera let's,
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imagine this is the digital sensor or
the piece of film.
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And let's, imagine that this is the
focal plane shutter.
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So the focal plane shutter will be
closed.
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And if we're going to run a shutter
speed of, say, a 30th of a second, it
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would go and open and close
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or a quarter of a second,
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and it would expose the sensor or the
film for that period of time.
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So no problem for the flash to fire and
expose
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the sensor
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during that period.
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But as the shutter gets faster, it
works slightly differently.
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It does not work by going
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much quicker and much quicker because
it cannot mechanically cope with those
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speeds.
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So what it does is it modifies its
operations slightly.
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The focal plane shutter
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traditionally has two shutter curtains,
there called.
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And what happens is, as the shutter
speed gets faster and faster, it cannot
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cope with the speed.
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So it changes the method in which it
works.
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And what it does
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is it opens the shutter, the bottom one
first,
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and then the top one
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will come down
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behind it
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very quickly.
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And what that does is it exposes just a
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strip
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of the sensor
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at a time, rather than exposing the
whole sensor, which is what happens on
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the slower shutter speeds.
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Now, because of this, this is a problem
for flash synchronization.
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Because if you can imagine, when the
shutter is fully open, the whole sensor
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can be exposed by the burst of flash.
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But when the shutter just opens as a
small slit, which is what it does on
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fast shutter, speeds like a 1000th or
2000th of a second, then only a small
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slit, or a scan
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of the sensor is actually taking place.
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And the problem with that
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is, if the flash fires, only a
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strip of the sensor is going to be
exposed by that flush.
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Now, if only a
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strip
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is going to be exposed by the flash, it
is going to result in parts of the
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image being blacked out by the actual
shutter itself.
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And this
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is the main problem of flash
synchronization.
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Speeds with the shutter in your camera.
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The problem is not the
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flush speed isn't fast enough, it's
that the mechanics of the shutter are
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changing to this
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slit formation,
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and the flash is unable to expose the
entire image in one exposure because of
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the slit.
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Now, recently,
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camera manufacturers and lighting
manufacturers have started to use a
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technique called high speed sync.
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This works slightly differently.
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What this does is allow for a longer
flashburst,
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that the flashburst
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last for the entire
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duration of the scan across the image.
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So rather than a short burst of flash,
the flash is set to actually expose for
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longer and more powerfully,
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so that the exposure
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coincides with the entire scan across
the image, across the sensor.
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Now this is kind of a fudge work
around, if you like, to overcome the
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problem of the slit.
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Now, on some other cameras, like medium
format cameras, it doesn't have this
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problem because the shutter is not
actually in the camera.
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The shutter is in the lens.
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And that type of shutter is called a
leaf shutter.
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And a leaf shutter opens and closes
just like an aperture.
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And it can do so more quickly.
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That means, on medium format cameras,
we can actually synchronize at any
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shutter speed, right up to the maximum
shushota speed, for example, like
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2000th of a second on the
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medium format household blood page six,
for example.
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So with medium format cameras, we don't
have the problem.
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On 35 mile cameras, we can now
overcome, overcome, the problem with
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high speed sync triggers, which I'm
going to show you shortly.
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But first of all, let's look at just
the current issue of flash sync speeds
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with an actual demonstration on our
dummy.
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So if I take a photograph on the
cannon, five d, mark three, with the
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standard trigger, and I've got the
shutter speed set to 100th of a second,
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I'm at f sixteen, I've got a monoblock
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studio flashhead here at power eight.
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And I'm just going to take a test shot
at 100th of a second.
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And let's look at the result on the
back of the camera.
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So here we can see that the
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dummy is exposed, or stiffening, as we
call it, is exposed correctly.
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And the flash power is fine for my
aperture setting of f 16.
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And we're at 100th of a second.
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Now let's see what happens as I
gradually
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increase that shutter speed.
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So I'm now going to change the shutter
speed to
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160th
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of a second
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and take the shot.
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And there we go.
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The result is exactly the same, which
is what I'd expect it to be.
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So even though we have an increase in
the shutter speed, the shutter speed
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doesn't really matter in this instance,
because it is the flash and the
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aperture that are controlling the
exposure.
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But let's see what happens as I start
to increase the shutter speed further.
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So this time, this time, I'm going to
go to 250th
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of a second, which is now beyond the
recommended sync speed.
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And look what started to happen.
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We have a black bar
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appear
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across our image, and it has blocked
out some of the shot.
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And this relates to what I was
demonstrating before, with the slip
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method of recording the image at higher
shutter speeds.
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So let's increase the shutter speed
further.
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We go to 640th
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of a second now,
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and there we go.
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So
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part of the image, a large part of the
image, is obscured.
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I'll drop to 400,
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there's
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another example.
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So what you're seeing, what you're
seeing there in that image
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is the actual
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shutter itself
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blanking out part of the image.
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Because we are now
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in the
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unacceptable shutter sync speeds.
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We're above the recommended sink speed,
where the entire sensor can be exposed
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in one
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00:11:03,830 --> 00:11:03,930
go.
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Now as I said recently,
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like broncolar have also produced a
high sync speed connection,
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which allows the flash to fire for a
longer period
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at a higher power output.
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To expose the entire sensor, even
though it's exposing through a, slit
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it's almost like a scan exposure.
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So let's see what happens when we
change the trigger and put it in high
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speed sink mode.
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So this is the Hs trigger.
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And we've just got a different flash
head in one of the Hs compatible ones.
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This is the cyros Lithium one, which is
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compatible with the high speed sync
mode.
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So I'm just going to turn that on,
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turn this on, make sure that the high
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speed sync mode is on.
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And let's take the picture again.
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So I'm going to start off where we
were.
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I think we're at about 640th
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of a second.
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Take the picture.
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Now it's dramatically overexposed at
the moment, because there's too much
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flash power.
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00:12:17,637 --> 00:12:21,7
So I'm going to turn the flash power
down and turn it down by a couple of
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stops.
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Let's take another one.
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And there we go.
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So now you can see that we have
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our
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model stiffany there
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exposed
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with the flash, even with a fast
shutter speed.
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Now I can increase that shut speed even
more.
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00:12:40,26 --> 00:12:42,896
So I'm going to increase it up to
2000th of a second,
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and it's a little bit darker.
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And the reason is that the slit would
have been
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thinner.
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00:12:51,471 --> 00:12:53,106
And the way that the
254
00:12:53,640 --> 00:12:57,610
shutter is working means that the
exposure is less.
255
00:12:58,411 --> 00:13:02,82
So to compensate, i'll now have to put
the flash power up
256
00:13:02,415 --> 00:13:02,982
a little bit.
257
00:13:02,982 --> 00:13:04,651
So I'm just going to take that up half
258
00:13:04,918 --> 00:13:05,452
a stop,
259
00:13:06,419 --> 00:13:07,354
take it again.
260
00:13:07,554 --> 00:13:08,488
And there we go.
261
00:13:08,655 --> 00:13:11,691
So we are able to expose
262
00:13:11,991 --> 00:13:12,625
with
263
00:13:13,626 --> 00:13:15,28
faster shutter speeds
264
00:13:15,862 --> 00:13:16,629
that have
265
00:13:17,130 --> 00:13:20,967
Hs enabled triggers and Hs enabled
266
00:13:21,267 --> 00:13:22,68
flashes.
267
00:13:22,502 --> 00:13:23,136
But as I explained,
268
00:13:24,170 --> 00:13:25,705
it is a bit of a work around.
269
00:13:25,939 --> 00:13:30,510
It's still not exposing the whole
sensor in one go in the traditional
270
00:13:30,910 --> 00:13:34,280
method, which is what happens when
you're working at sync speeds
271
00:13:36,583 --> 00:13:38,418
the recommended sync speed, where the
whole
272
00:13:39,719 --> 00:13:41,454
sensor is being exposed
273
00:13:41,688 --> 00:13:42,889
in one take.
274
00:13:43,690 --> 00:13:47,193
Ok, let's move on to our next
275
00:13:48,161 --> 00:13:48,795
segment.
276
00:13:50,196 --> 00:13:54,868
Ok, the next thing I want to look at is
the relationship of
277
00:13:55,235 --> 00:13:56,336
shutter speeds
278
00:13:56,903 --> 00:13:58,571
to the ambient exposure.
279
00:13:59,773 --> 00:14:04,844
And what I mean by the ambient exposure
is the existing light, that is the
280
00:14:04,911 --> 00:14:06,913
light that is there, that is not your
flashburst
281
00:14:07,947 --> 00:14:09,783
that's light, that is just on
permanently.
282
00:14:10,917 --> 00:14:16,423
So either the lights in your house, or
the sunlight outside, or daylight
283
00:14:16,823 --> 00:14:20,794
coming through your Windows, just
existing continuous light.
284
00:14:21,461 --> 00:14:25,298
Now to demonstrate this, I'm going to
switch on the
285
00:14:26,332 --> 00:14:31,204
fluorescent studio lights and the
ceiling lights so that we have a form of
286
00:14:31,705 --> 00:14:33,873
continuous light that I don't actually
like.
287
00:14:34,107 --> 00:14:36,42
And we're going to show you what
happens with that.
288
00:14:36,276 --> 00:14:39,846
But let me explain first a little bit
about what's going to happen.
289
00:14:40,280 --> 00:14:44,317
Now we know that if we use a sync speed,
290
00:14:44,751 --> 00:14:49,456
shutter speed, that the exposure is
made like soap, and the flash can
291
00:14:49,789 --> 00:14:51,858
expose the sensor in one go.
292
00:14:52,359 --> 00:14:56,262
Now generally speaking, our sync speeds
of 200th of a second
293
00:14:57,530 --> 00:15:02,502
or 250th on some of the modern digital
cameras, may even be 30400th
294
00:15:03,703 --> 00:15:04,104
of a second.
295
00:15:04,437 --> 00:15:07,240
And as I said, on medium format
cameras, it can be even faster.
296
00:15:08,41 --> 00:15:10,977
But generally speaking, those sync
speeds are sufficiently
297
00:15:12,412 --> 00:15:12,946
fast.
298
00:15:13,380 --> 00:15:14,414
They're fast enough
299
00:15:14,814 --> 00:15:19,719
to cut out the ambient light from
getting in and affecting our flash
300
00:15:19,953 --> 00:15:20,120
exposure.
301
00:15:20,820 --> 00:15:24,357
Unless, of course, you're working
outdoors in very bright sunlight.
302
00:15:24,991 --> 00:15:29,396
And that's why the high speed sync
modes can be useful to overcome that problem.
303
00:15:31,64 --> 00:15:35,135
If you're working with ordinary sync
speed modes, as say, generally, they
304
00:15:35,135 --> 00:15:37,871
would be fast enough to cut out the
existing light.
305
00:15:38,104 --> 00:15:41,941
But what happens when you start
dropping the shutter speed down to longer,
306
00:15:43,209 --> 00:15:44,344
slower, shutter speeds.
307
00:15:44,744 --> 00:15:45,111
So
308
00:15:47,480 --> 00:15:54,888
then a lot of ambient light is getting
in, as well as the light from your flush.
309
00:15:55,455 --> 00:15:59,459
And this then changes the overall look
of the image and the overall exposure,
310
00:16:00,26 --> 00:16:01,561
especially if you're working outdoors.
311
00:16:02,195 --> 00:16:05,632
But we're going to demonstrate it
indoors by turning on the ambient
312
00:16:06,32 --> 00:16:06,199
lights.
313
00:16:06,332 --> 00:16:08,1
We're going to turn on the fluorescent
light
314
00:16:08,335 --> 00:16:12,739
and show you what happens as we reduce
the shutter speed in combination with
315
00:16:12,739 --> 00:16:13,273
the flash.
316
00:16:19,212 --> 00:16:19,379
Ok?
317
00:16:19,713 --> 00:16:21,948
So I've turned on the fluorescent
318
00:16:23,149 --> 00:16:23,516
lamps
319
00:16:24,117 --> 00:16:25,485
in our studio ceiling.
320
00:16:26,186 --> 00:16:28,321
Now remember from the first chapter,
321
00:16:28,755 --> 00:16:32,759
when we looked at the spectrum of light
and the qualities of light, that these
322
00:16:32,892 --> 00:16:36,262
type of lights are not good for
photography because they're missing
323
00:16:36,830 --> 00:16:38,64
part of the spectrum.
324
00:16:38,732 --> 00:16:42,569
And what I'm going to do is I'm going
to show you the effect that they have now
325
00:16:42,902 --> 00:16:46,873
as I decrease, slow that shutter speed
down to longer shutter speeds,
326
00:16:47,73 --> 00:16:52,145
and we start to see some of this nasty
light building up on top of our flashlight.
327
00:16:52,345 --> 00:16:55,882
So we'll still be exposing our picture
with flashlight.
328
00:16:56,416 --> 00:16:59,452
Remember, the flashburst isn't going to
be affected by this, because the
329
00:16:59,452 --> 00:17:01,321
flashburst is very fast.
330
00:17:01,688 --> 00:17:04,991
So as I slow the shutterspeed, we're
not going to add any more flash.
331
00:17:05,625 --> 00:17:06,760
We're just going to add
332
00:17:07,227 --> 00:17:08,428
more ambient light.
333
00:17:08,728 --> 00:17:11,31
So let's look at that in practice.
334
00:17:14,501 --> 00:17:17,103
So just going to go back to the original
335
00:17:17,470 --> 00:17:17,637
trigger.
336
00:17:18,171 --> 00:17:21,274
We're not going to do this in high
speed sync mode.
337
00:17:21,775 --> 00:17:27,514
I'm going to go back to a conventional
sync speed of 160th of a second.
338
00:17:28,748 --> 00:17:29,282
And
339
00:17:30,417 --> 00:17:31,451
we'll start off at, say,
340
00:17:36,656 --> 00:17:37,924
let's take a test shot.
341
00:17:39,859 --> 00:17:40,593
And there we go.
342
00:17:40,660 --> 00:17:42,95
We can see the result there
343
00:17:42,729 --> 00:17:43,830
at f eleven
344
00:17:45,632 --> 00:17:48,268
with the test shot, we're at power 65.
345
00:17:49,302 --> 00:17:50,403
Can you come and see that?
346
00:17:51,371 --> 00:17:52,806
So there's our
347
00:17:53,239 --> 00:17:54,240
result of the flash,
348
00:17:55,709 --> 00:17:56,476
f 11160th
349
00:17:57,610 --> 00:17:58,78
of a second,
350
00:17:58,411 --> 00:17:58,912
and it's exposed
351
00:17:59,946 --> 00:18:01,614
just about right with flash.
352
00:18:01,948 --> 00:18:05,719
Now let's look what happens when I
lower that shutter speed.
353
00:18:06,119 --> 00:18:11,358
So I'm going to drop that shutter speed
down to a 40th of a second now.
354
00:18:13,693 --> 00:18:14,394
And now
355
00:18:14,828 --> 00:18:16,262
the exposure has got brighter.
356
00:18:16,896 --> 00:18:19,999
And if we compare that to the previous
shot, this is the most recent one,
357
00:18:20,333 --> 00:18:21,434
there's the one before.
358
00:18:21,868 --> 00:18:25,438
Now, all of that extra light you're
seeing isn't from the flash,
359
00:18:26,439 --> 00:18:27,874
because the flash isn't changing.
360
00:18:28,575 --> 00:18:32,12
The extra light you're seeing now is
from the
361
00:18:32,112 --> 00:18:32,912
ambient light.
362
00:18:33,146 --> 00:18:33,780
It's from the existing
363
00:18:34,914 --> 00:18:36,16
continuous light
364
00:18:36,583 --> 00:18:41,921
so as I increase this decrease, this
shutterspeed more and drop it even slower.
365
00:18:43,289 --> 00:18:47,193
So this time I'm going to drop it down
to 15th of a second.
366
00:18:49,529 --> 00:18:50,263
And there we go.
367
00:18:50,330 --> 00:18:54,834
At a 15th of a second, we can now start
to see this sort of yellowy, greeny
368
00:18:55,135 --> 00:18:56,336
build up of light
369
00:18:57,604 --> 00:18:58,405
compared
370
00:18:59,372 --> 00:19:00,940
to our original
371
00:19:02,242 --> 00:19:02,876
flash
372
00:19:03,143 --> 00:19:03,309
exposure.
373
00:19:03,777 --> 00:19:05,945
There was the original flash exposure
only.
374
00:19:07,80 --> 00:19:07,614
And then gradually
375
00:19:09,149 --> 00:19:13,453
this got brighter and brighter with the
addition of the
376
00:19:14,587 --> 00:19:15,855
fluorescent lamps.
377
00:19:16,489 --> 00:19:17,691
And you'll probably see it.
378
00:19:17,691 --> 00:19:19,793
If I zoom in here, we'll see it on the
shoulder.
379
00:19:20,427 --> 00:19:23,830
Let me just zoom in onto the image.
380
00:19:24,197 --> 00:19:29,803
If we take a look at these highlights
just here, I'm pretty sure these are
381
00:19:29,869 --> 00:19:33,406
from the fluorescent lights from the
studio ceiling.
382
00:19:33,540 --> 00:19:35,375
And if I go back a shot, there you go.
383
00:19:35,375 --> 00:19:35,775
They've disappeared.
384
00:19:36,509 --> 00:19:39,879
So they're not visible there because
the shutter speed was too fast.
385
00:19:40,413 --> 00:19:43,983
And then as I decrease the shutter
speed, we're starting to see the effect
386
00:19:44,351 --> 00:19:48,321
of the ambient light pouring into the
shot.
387
00:19:48,822 --> 00:19:51,558
Now, this is a common mistake with
photographers.
388
00:19:52,25 --> 00:19:55,95
When they're working indoors, they allow
389
00:19:55,628 --> 00:19:59,65
ambient light that shouldn't be there
to start affecting their picture.
390
00:19:59,799 --> 00:20:04,838
And they think it's actually the flash,
and they start adjusting the flesh exposure,
391
00:20:05,872 --> 00:20:07,240
thinking that it was the flash.
392
00:20:07,874 --> 00:20:13,313
And then they end up getting the wrong
balance of ambient light with flash c
393
00:20:14,414 --> 00:20:18,284
and not having the nice, clean, pure
light that you get from flash.
394
00:20:18,985 --> 00:20:23,857
Now there are many times where you do
want to combine ambient exposure with
395
00:20:24,24 --> 00:20:24,190
flash.
396
00:20:24,424 --> 00:20:27,961
For example, there's many outdoor
daylight Scenes where the light is pure
397
00:20:28,94 --> 00:20:32,32
and clean, and you want to incorporate
some of the daylight ambient in
398
00:20:32,198 --> 00:20:33,400
combination with your flesh.
399
00:20:34,434 --> 00:20:36,836
So in those situations it's perfectly
acceptable.
400
00:20:37,470 --> 00:20:41,241
But there are many situations where you
might be working with light that
401
00:20:41,241 --> 00:20:45,478
doesn't have a full spectrum, can give
a nasty colorcast, and that starts overpowering
402
00:20:46,513 --> 00:20:49,783
your flash because you have your
shutter speed set too slow.
403
00:20:50,183 --> 00:20:53,453
So just keep that in mind for future
reference.
404
00:20:57,290 --> 00:20:58,591
Ok, let's have a look.
405
00:20:58,658 --> 00:20:59,192
What's next.
406
00:21:00,960 --> 00:21:01,161
So
407
00:21:02,195 --> 00:21:04,464
we looked there at the
408
00:21:05,398 --> 00:21:10,403
effect of lowering the shutter speed,
and that lets more ambient light in.
409
00:21:10,670 --> 00:21:14,40
Now what you would have noticed is that
it does not affect flash power.
410
00:21:15,75 --> 00:21:16,976
Because the flash power is constant.
411
00:21:17,310 --> 00:21:18,44
It doesn't change.
412
00:21:18,511 --> 00:21:22,582
There is only one thing that changes
the flash power, and that's actually
413
00:21:22,982 --> 00:21:25,452
changing the power of the flash itself.
414
00:21:26,186 --> 00:21:30,657
Or actually the other thing is to move
the flash further away or closer will
415
00:21:30,757 --> 00:21:32,826
change the effective flash power.
416
00:21:33,393 --> 00:21:39,299
However, we can control the exposure of
the flash, not change its power, but we
417
00:21:39,299 --> 00:21:43,803
can control the exposure of the flash
by changing the aperture in the lens,
418
00:21:44,437 --> 00:21:48,842
if we adjust the aperture size, we're
either letting more light in or
419
00:21:48,908 --> 00:21:50,577
blocking some of that light out.
420
00:21:50,810 --> 00:21:54,848
And that will change the effective
power of the flash.
421
00:21:55,48 --> 00:21:58,351
It will change the appearance of the
flash because it is stopping some of
422
00:21:58,351 --> 00:21:59,219
the light getting in.
423
00:21:59,386 --> 00:22:01,921
So if we want to control flash exposure,
424
00:22:02,188 --> 00:22:04,190
we really have three ways of doing it.
425
00:22:04,591 --> 00:22:07,694
One, change the aperture setting on the
camera.
426
00:22:08,28 --> 00:22:11,64
Two, change the flash power on the
flash itself.
427
00:22:12,98 --> 00:22:14,267
And three, move the flash further
428
00:22:15,301 --> 00:22:17,103
or closer from the subject.
429
00:22:17,303 --> 00:22:20,173
So let's explore that a little bit as
well.
430
00:22:24,744 --> 00:22:26,880
So I'm going to go back to
431
00:22:28,748 --> 00:22:31,184
the flash sync speed of 165th of a
second.
432
00:22:32,185 --> 00:22:33,86
Take a test shot.
433
00:22:33,319 --> 00:22:35,689
We don't have any ambient light now,
only the
434
00:22:36,990 --> 00:22:38,358
video lights that we have on.
435
00:22:38,425 --> 00:22:42,829
But those are very clean, pure daylight
balance video lights, hmi lights, so
436
00:22:42,829 --> 00:22:44,164
they're absolutely fine.
437
00:22:44,431 --> 00:22:46,566
If we take a look at my test shot,
438
00:22:47,67 --> 00:22:49,302
here is the result on screen.
439
00:22:49,469 --> 00:22:51,4
I want to make it a little bit
brighter.
440
00:22:51,538 --> 00:22:51,705
Ok.
441
00:22:52,105 --> 00:22:56,743
So in this instance, I'm going to
increase the flush power by half a
442
00:22:56,743 --> 00:22:57,377
stop, from 6.5
443
00:22:58,11 --> 00:22:58,712
to seven.
444
00:22:58,912 --> 00:23:00,347
I'm going to take the shot again.
445
00:23:00,747 --> 00:23:03,383
And now the shot is a little bit
brighter than it was.
446
00:23:03,717 --> 00:23:05,118
There's the one before,
447
00:23:06,19 --> 00:23:07,354
and there's the one after.
448
00:23:07,854 --> 00:23:10,724
There's the one before, and there's the
one after.
449
00:23:11,691 --> 00:23:13,560
So I've adjusted the exposure
450
00:23:14,661 --> 00:23:17,797
only by changing the flash power.
451
00:23:18,431 --> 00:23:19,366
In that instance,
452
00:23:20,266 --> 00:23:21,768
however, I can
453
00:23:22,168 --> 00:23:26,673
change the effective flash power, or
what's visible, or what's recorded, by
454
00:23:26,673 --> 00:23:27,540
changing the aperture.
455
00:23:28,174 --> 00:23:28,675
In the lens,
456
00:23:29,876 --> 00:23:31,644
the aperture is different to the
shutter.
457
00:23:32,178 --> 00:23:35,48
If I change the aperture, now, from f
eleven
458
00:23:35,548 --> 00:23:38,818
to f eight, i'll go one stop brighter.
459
00:23:39,52 --> 00:23:40,787
I'm letting in one stop more light,
460
00:23:41,721 --> 00:23:43,356
and now the picture is
461
00:23:43,690 --> 00:23:45,859
one stop brighter from what it was.
462
00:23:46,359 --> 00:23:49,396
So now, f eight that's the exposure I'm
getting from the flash.
463
00:23:49,929 --> 00:23:51,297
That's what it was at f eleven.
464
00:23:52,98 --> 00:23:55,201
So I'm letting in more flash power,
465
00:23:55,769 --> 00:23:59,706
but I'm also letting in any more
ambient as well.
466
00:24:00,40 --> 00:24:03,710
So with the aperture, when we open the
aperture, we are, of course, letting
467
00:24:04,177 --> 00:24:06,980
any type of light in, whether it's
flash or ambient.
468
00:24:07,614 --> 00:24:10,583
So if I wanted to work at f eight,
which, as we can see
469
00:24:11,618 --> 00:24:15,622
here, is one stop over exposed, if I
want that to be my desired aperture.
470
00:24:16,89 --> 00:24:18,658
Then i'll need to turn the flash power
down one stop
471
00:24:19,693 --> 00:24:20,960
to power six.
472
00:24:21,795 --> 00:24:26,399
And i'll take the shot again, and i'll
now arrive back at the correct exposure.
473
00:24:27,67 --> 00:24:28,168
So that's
474
00:24:28,568 --> 00:24:31,705
two methods of adjusting the flash
exposure.
475
00:24:32,439 --> 00:24:35,842
The third method is simply the flash to
subject distance.
476
00:24:36,276 --> 00:24:39,679
If I now want this shot to be brighter
than that,
477
00:24:39,946 --> 00:24:40,513
I could alternatively
478
00:24:41,948 --> 00:24:42,716
move the flash
479
00:24:43,49 --> 00:24:43,983
closer,
480
00:24:44,818 --> 00:24:45,752
take the shot.
481
00:24:45,952 --> 00:24:46,986
Let's just compare the original.
482
00:24:47,320 --> 00:24:49,122
There's the original that we just shot
last.
483
00:24:49,289 --> 00:24:50,390
Take the new shot,
484
00:24:50,890 --> 00:24:51,991
and now it's brighter.
485
00:24:52,492 --> 00:24:53,593
Here's the new shot.
486
00:24:54,661 --> 00:24:55,628
There's the old shot.
487
00:24:56,429 --> 00:24:57,764
There's the new shot,
488
00:24:58,331 --> 00:24:59,366
there's the old shot.
489
00:24:59,799 --> 00:25:02,235
Now I haven't changed the flash power.
490
00:25:02,902 --> 00:25:05,271
I just moved it a few feet closer.
491
00:25:05,872 --> 00:25:09,776
And by moving it closer, remember the
inverse square law, we are adjusting
492
00:25:10,510 --> 00:25:10,744
the power
493
00:25:11,945 --> 00:25:15,482
if we're moving the flash source closer
to our subject.
494
00:25:16,116 --> 00:25:18,351
So those are the three ways that we can
control
495
00:25:19,386 --> 00:25:24,324
the effective flash power by actually
changing the power, changing the aperture
496
00:25:24,491 --> 00:25:26,226
or changing the distance.
497
00:25:29,396 --> 00:25:29,562
Ok.
498
00:25:29,863 --> 00:25:31,631
So now we're going to look at
499
00:25:32,432 --> 00:25:36,102
first curtain and second curtain,
synchronization of the flash.
500
00:25:36,670 --> 00:25:38,338
This is someone sometimes called
501
00:25:39,639 --> 00:25:41,307
rear sink curtain as well.
502
00:25:41,775 --> 00:25:43,777
Let me explain what that means.
503
00:25:44,277 --> 00:25:46,413
Now, if we're doing long exposures,
504
00:25:46,680 --> 00:25:49,115
like a shutter speed of, say, a second,
505
00:25:51,384 --> 00:25:53,153
then we're exposing for quite a long
time.
506
00:25:53,853 --> 00:25:57,390
And existing light like this one, which
is a continuous light.
507
00:25:57,457 --> 00:25:59,959
This is our video light to hmi light
there.
508
00:26:00,360 --> 00:26:02,395
So this is giving continuous light
509
00:26:02,662 --> 00:26:04,998
that will be recorded during the long
exposure.
510
00:26:05,799 --> 00:26:08,1
But we can combine that with flash,
511
00:26:08,735 --> 00:26:11,504
but we can choose whether the flash
goes off at the
512
00:26:11,871 --> 00:26:13,606
start of the exposure
513
00:26:14,174 --> 00:26:16,42
or at the end of the exposure.
514
00:26:16,810 --> 00:26:20,513
And that has a big difference in
bearing on the resulting photograph.
515
00:26:20,914 --> 00:26:22,248
Let me explain why.
516
00:26:22,582 --> 00:26:25,585
So for example, if I was walking along
here
517
00:26:26,419 --> 00:26:28,588
on a long, one second exploit exposure,
518
00:26:29,689 --> 00:26:34,194
then my image would be recorded as a
trail, as a blur from the continuous
519
00:26:34,828 --> 00:26:34,994
light.
520
00:26:35,628 --> 00:26:38,565
But if we pop a bit of flash in there
as well,
521
00:26:38,732 --> 00:26:39,399
i'll be frozen
522
00:26:40,500 --> 00:26:42,569
at the point when the flash went off.
523
00:26:43,69 --> 00:26:44,804
But if I'm walking this way
524
00:26:45,138 --> 00:26:47,707
and the flash goes off at the start of
my exposure
525
00:26:48,742 --> 00:26:53,146
pop, then I'm frozen here, and then I'm
blurred here will actually look like
526
00:26:53,146 --> 00:26:55,849
I'm walking backwards, even though as
walking forwards.
527
00:26:56,182 --> 00:27:00,687
So in those instances, we're better to
switch to rear curtain or second
528
00:27:00,820 --> 00:27:02,88
curtain synchronization
529
00:27:02,255 --> 00:27:06,192
and then what that means is that the
exposure will start, I will be recorded
530
00:27:06,593 --> 00:27:10,430
with the continuous light, and then
just before the shutter closes, the
531
00:27:10,430 --> 00:27:11,231
flash will fire.
532
00:27:11,531 --> 00:27:14,501
Then, and then the trail will be the
right direction.
533
00:27:15,235 --> 00:27:17,70
And who better to demonstrate it for
us?
534
00:27:17,137 --> 00:27:19,506
Let's get Mr over to do some test shots.
535
00:27:20,273 --> 00:27:22,676
So we'll look at the camera menu.
536
00:27:22,976 --> 00:27:24,811
I'm just going to go into the menu,
537
00:27:25,779 --> 00:27:29,749
and I'm going into external speed, like
control
538
00:27:30,817 --> 00:27:31,885
flash function settings.
539
00:27:32,519 --> 00:27:37,123
And in flash function settings, I need
to get across to this one
540
00:27:37,557 --> 00:27:39,826
and choose first curtain
synchronization,
541
00:27:40,193 --> 00:27:41,227
or second curtain synchronization.
542
00:27:42,429 --> 00:27:45,799
In this instance, to show you the wrong
way of doing it, I'm going to go with
543
00:27:45,799 --> 00:27:48,1
first curtain synchronization to start
with.
544
00:27:48,435 --> 00:27:53,606
So I'm just going to get Emma to walk
across in a straight line now.
545
00:27:55,475 --> 00:27:59,45
And if we look at the result there, you
can see she's frozen,
546
00:27:59,612 --> 00:28:01,448
and then there is the blurred
547
00:28:02,115 --> 00:28:02,282
image.
548
00:28:02,582 --> 00:28:02,749
Trail.
549
00:28:03,149 --> 00:28:05,385
You do that again, come a little bit
closer this way.
550
00:28:05,385 --> 00:28:06,119
That's it right?
551
00:28:06,186 --> 00:28:07,53
Off you go again.
552
00:28:08,822 --> 00:28:09,756
So there was the flash.
553
00:28:10,490 --> 00:28:12,158
So there she's frozen, sharp,
554
00:28:12,759 --> 00:28:13,560
and then she's blurred.
555
00:28:13,793 --> 00:28:13,960
Slow.
556
00:28:14,94 --> 00:28:15,695
You walk down a little bit this time.
557
00:28:18,998 --> 00:28:20,900
So, and again, a little bit closer.
558
00:28:21,234 --> 00:28:21,634
That's it?
559
00:28:21,701 --> 00:28:22,602
Just stay on that line.
560
00:28:22,736 --> 00:28:23,203
There
561
00:28:23,503 --> 00:28:24,4
ok,
562
00:28:27,73 --> 00:28:27,640
there we go.
563
00:28:27,640 --> 00:28:28,808
So she's frozen,
564
00:28:29,542 --> 00:28:30,443
and then the image trail.
565
00:28:30,577 --> 00:28:33,546
So the image trail looks like it's
going the wrong way because the flash
566
00:28:33,947 --> 00:28:36,316
fired at the start of my exposure.
567
00:28:36,583 --> 00:28:41,321
So now I'm going to go into the menu,
I'm going to choose external speed like
568
00:28:41,388 --> 00:28:44,491
control, I'm going to choose flash
function settings,
569
00:28:44,758 --> 00:28:48,528
and I'm going to change to second
curtain synchronization.
570
00:28:49,462 --> 00:28:51,197
And now as Emma walks,
571
00:28:53,633 --> 00:28:55,835
the flash fired at the end of the
exposure.
572
00:28:56,169 --> 00:28:59,139
Now we can see the image blur the
correct way.
573
00:28:59,639 --> 00:29:03,943
So now we see the blur behind Emma,
rather than in front of Emma.
574
00:29:04,411 --> 00:29:09,49
This gives the suggestion that she's
walking in the right direction and that
575
00:29:09,49 --> 00:29:11,151
the trail, the blur, is in the right
direction.
576
00:29:11,451 --> 00:29:12,152
Let's go again.
577
00:29:14,988 --> 00:29:15,722
And here we go.
578
00:29:16,189 --> 00:29:21,695
There's the trail blur, and then
there's Emma frozen at the end of the
579
00:29:21,695 --> 00:29:21,861
exposure.
580
00:29:22,429 --> 00:29:26,99
So a very simple technique often
misunderstood, it's called first
581
00:29:26,266 --> 00:29:28,201
curtain or rear curtain, or second
curtain synchronization.
582
00:29:28,902 --> 00:29:32,906
And it's whether the flash fires at the
start of the shutter opening, or
583
00:29:32,972 --> 00:29:36,943
whether it fires at the end when the
shutter is just about to close.
46862
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