Is X-Sync speed a "big deal" anymore - now that we have High-speed synch on powerful flash units?

Skip M wrote:

?? On my flash meter, I set the shutter speed required, the meter matches
that with the appropriate aperture, since all it can measure is the amount
of light, not the speed of the shutter. There is an interconnection between
the shutter speed and the aperture, and, while shutter speed is less
important in the studio than in the field, because of the ease of
controlling the light, you still need to be able to change the shutter speed
to compensate for the aperture. If the fastest available shutter speed is
1/200, it is hard to get to f2.8 with strobes that only have a range of 2
stops.

That doesn't make sense. For flash exposure the shutter speed is
unimportant; exposure will be the same at 1/125 as at 1/250 or 1/60, with
the same aperture, unless ambient light is also contributing. Getting
f/2.8 with strobes has nothing whatever to do with the shutter speed.

--
Jeremy |

In message ,
"C J Southern" wrote:

The only limitation I hit was the 580EX not being able to cycle fast enough
when I fired a burst of shots.

There is another limitation, which can be quite serious when trying to
stop action. If you are set to 1/320, etc, the duration of the flash
can be many times as long as it is with normal sync, so 1/320 can give
much more motion blur *and* possibly staggered into vertical strips)
than with normal sync (which can be as fast as something like 1/10000).
After all, HP sync is merely a strobe that lights the scene for as long
as the shutter is open; not a single pulse of light that illuminates the
frame all at once.

With this in mind, it begs me to ask the question: "Is an X-Sync speed of
"this" or "that" simply irrelivant in this day and age?

Additionally, can anyone think of a reason why Canon couldn't even give us a
custom function that says "Use FP Mode when 1/250 of a Sec"?

I don't know about the 580EX, but the 550EX works just that way. It
only uses high-speed sync if it is enabled on the flash, *and* the
camera is set to a fast shutter speed. If the flash is on, but
high-speed sync is not, then the camera won't honor your chosen shutter
speed, and give you the normal sync speed instead. If high-speed is on,
and the shutter speed is less than the sync speed, then normal sync is
always used.
--


John P Sheehy

In message ,
"C J Southern" wrote:

"Jeremy Nixon" wrote in message
...

High-speed sync works differently from normal flash mode in that the flash
actually becomes "slower" -- it fires multiple pulses instead of a single
flash, and thus is not good for stopping motion -- the exposure time is
actually controlled by the shutter speed, whereas the flash duration is
much shorter in normal mode.

Then again, if you're shooting with a shutter speed of upwards of 1/250th,
isn't that going to freeze most motion anyway?

1/320 is about 30x as long as the shortest normal sync flash possible,
and will not stop a swung baseball bat, or the wing of a bird in motion
(or even its head).

In addition, the frame is exposed in vertical strips over a period
slightly longer than the stated exposure time with high-speed (as is
also true of ambient light exposures faster than the sync speed, as
well).
--


John P Sheehy

In message ,
"C J Southern" wrote:

"Since only a fraction of the light at any time is exposing the film or CCD
you lose a lot of light, again getting you back to the problems of limited
flash range" - Others have said "you lose about 1/3" (personally, I wouldn't
know) - again, with multiple, powerful units like the 580EX I wondr how much
of an issue this is?

With the 20D and 550EX, normal-sync GN (at 105mm) is 55 (meters), and
drops to 24.3 at 1/320. GN at 1/8000 is 4.9.
--


John P Sheehy

"Alan Browne" wrote in message
...
Skip M wrote:


?? On my flash meter, I set the shutter speed required, the meter
matches that with the appropriate aperture, since all it can measure is
the amount of light, not the speed of the shutter. There is an
interconnection between the shutter speed and the aperture, and, while
shutter speed is less important in the studio than in the field, because
of the ease of controlling the light, you still need to be able to change
the shutter speed to compensate for the aperture. If the fastest
available shutter speed is 1/200, it is hard to get to f2.8 with strobes
that only have a range of 2 stops.

I'm sure this is not news to you Skip:

In flash work, aperture controls both flash and ambient light, but shutter
speed contols _only_ ambient light.

This is why, for most flash photography where ambiient is not desired,
that the max sync speed is used. (And the beauty of leaf shutters with
studio strobes).

If your studio strobes have limited control (like mine) then you sew extra
softbox difusers, bounce the light off of white cardboard, use ND's or
slower film to get those fat apertures...

My flash meters (Minolta VF and Sekonic 508 and 558) have a "ratio"
reading for flash v. ambient. For most studio work, the ratio is 100%
flash, but if you reduce the shutter speed enough, then the flash content
drops (of course).

Cheers,
Alan.



One thing I forgot about was ISO 50 on the 5D, that would get me an extra
stop on the aperture. I'll have to try that.
Part of my problem, besides the limited control, is the size of my "studio."
It's my 11'x14' family room. Not enough room for a lot of devices.
That, and I'm learning on the run...

--
Skip Middleton
http://www.shadowcatcherimagery.com

"Jeremy Nixon" wrote in message
...
Skip M wrote:

?? On my flash meter, I set the shutter speed required, the meter
matches
that with the appropriate aperture, since all it can measure is the
amount
of light, not the speed of the shutter. There is an interconnection
between
the shutter speed and the aperture, and, while shutter speed is less
important in the studio than in the field, because of the ease of
controlling the light, you still need to be able to change the shutter
speed
to compensate for the aperture. If the fastest available shutter speed
is
1/200, it is hard to get to f2.8 with strobes that only have a range of 2
stops.

That doesn't make sense. For flash exposure the shutter speed is
unimportant; exposure will be the same at 1/125 as at 1/250 or 1/60, with
the same aperture, unless ambient light is also contributing. Getting
f/2.8 with strobes has nothing whatever to do with the shutter speed.

--
Jeremy |

Like I said earlier, I'm still learning this part, not real experienced with
studio strobes. I'll try that, next time.

--
Skip Middleton
http://www.shadowcatcherimagery.com

"Alan Browne" wrote in message
...
Skip M wrote:

The relevance come in when you are working in the studio with strobes,
and a faster shutter speed would allow you to lessen your depth of field.

Studio strobes don't have HSS. You charge them to the energy level
required and they dump completely (opposite of TTL/E-TTL flashes that are
fully charged and dump down to a point cut off by the thyristor under
command of the camera exposure system).

You can dial your strobes down and/or put covers over them to lessen the
light output and/or add ND's to the lens to get those fat aperture shots.

Cheers,
Alan




Thanks, like I said, I'm still learning on the run with some of this
stuff...

--
Skip Middleton
http://www.shadowcatcherimagery.com

Skip M wrote:

Like I said earlier, I'm still learning this part, not real experienced with
studio strobes. I'll try that, next time.

With strobes, the exposure time is irrelevant because the exposure time is
determined by the flash, which is (necessarily) of shorter duration than
the actual shutter speed. You can set any speed up to the camera's maximum
sync speed, and it doesn't matter in terms of exposure; the reading on the
light meter for aperture is all that matters.

The meter has a shutter speed indication because it also measures ambient
light and determines the amount of contribution it makes to the overall
exposure. Shutter speed does matter for any ambient light, of course.
In a typical studio setup, the ambient light contribution will be zero.
My meter indicates this by saying "100%" for the flash contribution.
Decent studio strobes will shut off the modeling light when they flash,
so even those won't affect the image. (What's interesting about that
is that it's too fast to see; I "know" mine shuts off the modeling light
because it says it does, but I never actually noticed it. I'd imagine
that you could use a slow enough shutter speed to catch the modeling
lights on; obviously the power pack has no idea what your shutter speed
is set for.)

Older flash meters like the ones I learned with don't have any shutter
speed setting or indication because they measured only the flash.

--
Jeremy |

"Jeremy Nixon" wrote in message
...
Skip M wrote:

Like I said earlier, I'm still learning this part, not real experienced
with
studio strobes. I'll try that, next time.

With strobes, the exposure time is irrelevant because the exposure time is
determined by the flash, which is (necessarily) of shorter duration than
the actual shutter speed. You can set any speed up to the camera's
maximum
sync speed, and it doesn't matter in terms of exposure; the reading on the
light meter for aperture is all that matters.

Ok, I get that, now. I took a lighting class a few years ago, but didn't
use strobes then, and that part of the class didn't penetrate, apparently.
But it's coming back to me, as I read what you wrote.

The meter has a shutter speed indication because it also measures ambient
light and determines the amount of contribution it makes to the overall
exposure. Shutter speed does matter for any ambient light, of course.
In a typical studio setup, the ambient light contribution will be zero.
My meter indicates this by saying "100%" for the flash contribution.
Decent studio strobes will shut off the modeling light when they flash,
so even those won't affect the image. (What's interesting about that
is that it's too fast to see; I "know" mine shuts off the modeling light
because it says it does, but I never actually noticed it. I'd imagine
that you could use a slow enough shutter speed to catch the modeling
lights on; obviously the power pack has no idea what your shutter speed
is set for.)

That makes sense, now. My meter does that, too. I'm guessing that my
strobes do, too, but I've no confirmation of that. OTOH, the modeling light
is so weak that I'm not sure what difference it would make. It's about 100
watts.

Older flash meters like the ones I learned with don't have any shutter
speed setting or indication because they measured only the flash.

I just started using strobes late last year, it's not something I'm familiar
with, obviously. When I started working with studio stuff, strobes were out
of my budget, so I stuck to floods. The price has come down, and my budget
has gone up to meet it, but I appreciate the help. I have a shoot coming up
that I'll put this to use for.
Thanks,
--
Skip Middleton
http://www.shadowcatcherimagery.com

"zeitgeist" wrote in message
...

somehow I don't think that HP sync works with slaved flash so you won't
get
any key fill light.

It works fine with the ST-E2 Transmitter and 580EX Flashes. It's a setting
on the transmitter - you don't even have to adjust the 580s.