canon 20D flash sync at 1/320?

peter wrote:
> When I attach a canon speedlite 550ex (high speed sync off) on a 20D, the
> shutter speed automatically reduced to 1/250s if I had it faster.
>
> Is there a way to override this?
>
> I found by experiment, I can flash sync at 1/320s (the experiment is done
> with a 3rd party flash that does not change the shutter speed). So I would
> like to use this speed with the canon speedlite, but it won't let me.
>
> Any ideas? I checked all the custom functions and none of them look like it
> would help.

High speed synch should be turned on.

--
john mcwilliams
 >> Stay informed about: canon 20D flash sync at 1/320? 

peter wrote:
> When I attach a canon speedlite 550ex (high speed sync off) on a 20D, the
> shutter speed automatically reduced to 1/250s if I had it faster.
>
> Is there a way to override this?
>
> I found by experiment, I can flash sync at 1/320s (the experiment is done
> with a 3rd party flash that does not change the shutter speed). So I would
> like to use this speed with the canon speedlite, but it won't let me.
>
> Any ideas? I checked all the custom functions and none of them look like it
> would help.

As I'm sure you know, flash sync speed is driven by shutter mechanics.
Faster shutters allow faster sync speeds, the best for FP shutters being
1/300 (Minolta, Nikon). Canon max sync speeds are 1/250. (Some Nikon
dslr's like the D70 also have electronic shuttering in the way they use
the sensor thereby achieving 1/500 flash sync).

It's tough doing fast shutters. Nikon have reduced the max sync in the
F6 to 1/250 from 1/300 (F5). OTOH, the added value is also questionable.

With my Maxxum 9 (flash sync=1/300) I can get 1/350 shots using the
flash sync terminal. With my Maxxum 7D (flash sync=1/160) I can get
1/200. With a Maxxum flash it of course limits it to 1/300 and 1/160
respectively (and 1/125 with anti-shake activated).

With that and your experience it's reasonable to assume that the max
shutter speed is conservative by 1/3 to 2/3 of a stop to allow for
manufacturing variance, environment (temperature) and aging.

Bret and John recommend high-speed sync but that reduces your available
power considerably, esp. when you get to 1/1000 and faster. Most of the
flash light is wasted on the shutter curtains... it remains a good way
to get shallow DOF on bright scenes where you want some action freeze
and fill in the foreground.

But then so does a ND filter with normal sync flash... and paradoxically
due to the great inefficiency of HSS, you'll actually save flash
batteries with a 2 stop ND in place once you're at 1/1000 (or so) and
faster.

Cheers,
Alan

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 >> Stay informed about: canon 20D flash sync at 1/320? 

peter <nospam.DeleteThis@nospam.com> wrote:
>When I attach a canon speedlite 550ex (high speed sync off) on a 20D, the
>shutter speed automatically reduced to 1/250s if I had it faster.
>
>Is there a way to override this?

It's hard to know why you would want to.

>I found by experiment, I can flash sync at 1/320s (the experiment is done
>with a 3rd party flash that does not change the shutter speed). So I would
>like to use this speed with the canon speedlite, but it won't let me.

That's because 1/250s is the flash sync speed for that camera, and it
will adjust the sutter speed accordingly.

And, as a practical matter, it rarely matters much anyway sicne the
flash speed it so much faster than the shutter. If you want to reduce
non-flash light then you can also reduce the aperture or use a neutral
density filter. Or turn off the lights.

--
Ray Fischer
rfischer.DeleteThis@sonic.net
 >> Stay informed about: canon 20D flash sync at 1/320? 

"Annika1980" <annika1980.DeleteThis@aol.com> wrote in message
news:1179557497.596119.184130@h2g2000hsg.googlegroups.com...
> On May 19, 1:14 am, "peter" <nos....DeleteThis@nospam.com> wrote:
>> When I attach a canon speedlite 550ex (high speed sync off) on a 20D, the
>> shutter speed automatically reduced to 1/250s if I had it faster.
>>
>> Is there a way to override this?
>>
>> I found by experiment, I can flash sync at 1/320s (the experiment is done
>> with a 3rd party flash that does not change the shutter speed). So I
>> would
>> like to use this speed with the canon speedlite, but it won't let me.
>>
>> Any ideas? I checked all the custom functions and none of them look like
>> it
>> would help.
>
> Turn high speed sync on. That's why they call it high speed sync.

I don't want to, that why I turn it off.
High speed sync is less powerful than low speed sync. Cheating the sync
speed is equivalent to boosting the flash's output power when used as a fill
flash.

Don't know why canon won't allow it even in manual mode. Why is it called
manual mode if the shutter speed is changed automatically for me??
 >> Stay informed about: canon 20D flash sync at 1/320? 

"Alan Browne" <alan.browne.RemoveThis@FreelunchVideotron.ca> wrote in message
news:0pE3i.91524$wo4.183836@wagner.videotron.net...
>
> With that and your experience it's reasonable to assume that the max
> shutter speed is conservative by 1/3 to 2/3 of a stop to allow for
> manufacturing variance, environment (temperature) and aging.
>
> Bret and John recommend high-speed sync but that reduces your available
> power considerably, esp. when you get to 1/1000 and faster. Most of the
> flash light is wasted on the shutter curtains... it remains a good way to
> get shallow DOF on bright scenes where you want some action freeze and
> fill in the foreground.
>
> But then so does a ND filter with normal sync flash... and paradoxically
> due to the great inefficiency of HSS, you'll actually save flash batteries
> with a 2 stop ND in place once you're at 1/1000 (or so) and faster.

Thanks, you're the only reply that understands my need (almost). I do plan
to use a ND filter to reduce DOF.

If I can cheat the sync speed, I could effectively reduce the sunlight's
intensity and enable fill-in flash at greater shooting distance, or save
flash power at the same distance (battery pack last longer), and less
blinding flash into the subjects' eyes.

This auto-limiting sync speed in *manual mode* reminds me of parents who
tell their child they can do whatever they want, and then meddle in the
child's business.
 >> Stay informed about: canon 20D flash sync at 1/320? 

peter wrote:
> I do plan
> to use a ND filter to reduce DOF.

How does an ND filter reduce depth of field?

Roger
 >> Stay informed about: canon 20D flash sync at 1/320? 

John McWilliams <jpmcw RemoveThis @comcast.net> wrote in
news:MdednWyLZ9_-Y9PbnZ2dnUVZ_vvinZ2d@comcast.com:

> High speed synch should be turned on.

High speed sync has many problems. It has a much lower GN, even at just
1/3 stop faster than the x-sync (and gets progressively worse with faster
shutter speeds). It wastes power, with the majority of light at any given
time falling on the shutter curtains instead of the sensor. It has no
action-stopping power, beyond the shutter speed, as it is basically just an
auxilliary pulsing lamp.

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS RemoveThis @no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
 >> Stay informed about: canon 20D flash sync at 1/320? 

In article <mZI3i.2154$Ud7.1334@trnddc08> "peter" <nospam RemoveThis @nospam.com> writes:
$Don't know why canon won't allow it even in manual mode. Why is it called
$manual mode if the shutter speed is changed automatically for me??

Remember that the output of a flash is controlled not by adjusting
its intensity but by adjusting its duration. The more power you want,
the longer the flash is on. The camera's maximum X-sync speed has to
be designed such that it will not cause problems with the longest
possible flash burst, which will depend on the flash unit but is
usually more than 1 ms and perhaps as much as 2 ms. With the flash
taking that long, that means that in order to achieve a maximum X-sync
speed of 1/250, the shutter curtains must be able to make their full
motion in 2 ms (during the first 2 ms, the first curtain opens; for
the next 2 ms, the shutter is fully open; during the next 2 ms, the
second curtain closes). 2 ms isn't a lot of time to take a physical
device, accelerate it from rest to full speed and have it
traverse the opening.

Chances are that if you fire a full-power flash burst with the
shutter speed set to 1/320, the second curtain is going to start
closing before the flash has completed firing. Now, since flash
output rises rapidly and falls slowly, the part of the flash burst
that you're blocking as the second curtain starts to close is quite
dim and likely will be very hard to spot in the results - but it's
nevertheless not syncing correctly.

On the other hand, if you fire a partial-power burst, it will take
quite a bit less time, perhaps much less than 1 ms, and in this case
there *is* enough time for the flash to complete before the second
curtain starts to close, even at a shutter speed above maximum X-sync.

As for why the camera doesn't allow you to pick a higher sync speed
at least some of the time, well, the camera doesn't know how long the
flash burst will be. That's controlled by the flash. And the flash
may not know, either; among other things, it depends on whether you let
the capacitor charge fully before firing the flash. The camera and
the flash don't even know at what strength to fire the flash until
flash metering is done, which (unless you use flash exposure lock)
doesn't happen until after the ambient exposure value has already
been set.

Anyway, the bottom line is that the camera's specs clearly indicate
that 1/250 is the maximum X-sync speed. If you expected something
else, you were mistaken. If you absolutely need to use a flash along
with a shutter speed that's only a third of a stop above what the
specs say, go ahead and use a non-dedicated flash (the camera doesn't
know it's there and therefore will not impose the maximum X-sync
limit) and hope for the best.
--
Stephen M. Dunn <stephen RemoveThis @stevedunn.ca>
>>>----------------> http://www.stevedunn.ca/ <----------------<<<
------------------------------------------------------------------
Say hi to my cat -- http://www.stevedunn.ca/photos/toby/
 >> Stay informed about: canon 20D flash sync at 1/320? 

On Sat, 19 May 2007 22:08:34 -0700, Roger N. Clark, who cannot
possibly see this reply as anything other than a personal attack,
(change username to rnclark) wrote:

>> I do plan to use a ND filter to reduce DOF.
>
> How does an ND filter reduce depth of field?

You should know the answer to that quite well. A larger aperture
produces a smaller DOF. Depending on conditions (lack of tripod,
slow shutter speed required for shot, already using lowest ISO,
excessively bright day) it may be difficult or impossible to
increase the aperture unless an ND filter is available.

Technically, and rather obviously, an ND filter by itself has no
effect on the DOF. Cameras have many interrelated attributes (think
ISO/noise), but in the process of trying to show your mastery of all
things photographic by winning an easy debating point, you show that
once again a clear response that actually helps people probably
isn't the primary goal. The flash complicates matters, and if you
think that it would somehow prevent an ND filter from helping the OP
to get a shallower DOF, it would have been nice to explain why,
rather than baiting the OP with your question. You have better
things to do, and as I've said elsewhere, Floyd is currently on a
roll. Why not help him out. He needs you, desperately.
 >> Stay informed about: canon 20D flash sync at 1/320? 

ASAAR wrote:
<attack deleted>
> Technically, and rather obviously, an ND filter by itself has no
> effect on the DOF.

Of course I know how an ND might be used too change
DOF. I posted a simple question to see how the OP
was using an ND with a flash. It is not a simple
problem, and the ND does not itself change DOF.
From his response, it might open other dialog,
but with your attack, he is probably scared off.

To the OP: some people in this newsgroup seem only
out to attack other people, and waste a lot of
space and often destroy discussions. The
attack by ASAAR is yet another example.

Roger
photos at: http://www.clarkvision.com
 >> Stay informed about: canon 20D flash sync at 1/320? 

On Sun, 20 May 2007 05:10:08 -0700, Roger N. Clark (change username
to rnclark) wrote:

> Of course I know how an ND might be used too change
> DOF. I posted a simple question to see how the OP
> was using an ND with a flash. It is not a simple
> problem, and the ND does not itself change DOF.
> From his response, it might open other dialog,
> but with your attack, he is probably scared off.

And of course you saw my reply as an "attack", just as I predicted
you would.


> To the OP: some people in this newsgroup seem only
> out to attack other people, and waste a lot of
> space and often destroy discussions. The
> attack by ASAAR is yet another example.

And as usual, your knee-jerk reaction is not to open the dialog
that you profess to prefer, but to turn an imaginary attack into a
real one.
 >> Stay informed about: canon 20D flash sync at 1/320? 

On May 20, 10:18 pm, nob....TakeThisOut@noplace.org wrote:
> Another resounding reason (among dozens) of why I went with advanced P&S cameras
> instead of DSLRs when I switched from film to digital. On my Sony I can shoot
> with flash (IN SYNC) up to 1/2000th of a second.

How about posting some of those Mavica shots so we can have a laugh
(oops, I meant a "look").
 >> Stay informed about: canon 20D flash sync at 1/320? 

ASAAR wrote:

> And as usual, your knee-jerk reaction is not to open the dialog
> that you profess to prefer, but to turn an imaginary attack into a
> real one.

Hmm.... Let's see who did the "knee-jerk" reaction.

A simple question:
Roger N. Clark wrote:
> How does an ND filter reduce depth of field?

It was an honest question. While I carry an ND filter
as standard, I have never used one for such an application
with a flash. The ND reduces the flash power reducing
flash range, so it is not a simple answer. Perhaps
the OP has some insight.

Your response:
ASAAR wrote:
> but in the process of trying to show your mastery of all
> things photographic by winning an easy debating point, you show that
> once again a clear response that actually helps people probably
> isn't the primary goal.

You are the one with the knee-jerk reaction, and further proof
you are a troll waiting to pounce on people at your slightest
perception of wrongdoing. You are ruining this newsgroup.

I come here to learn, and sometimes I can help teach in the
areas where I have some expertise.

Roger
 >> Stay informed about: canon 20D flash sync at 1/320?