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Slave Flash

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Anonymous
February 20, 2005 10:25:12 PM

Archived from groups: rec.photo.digital (More info?)

Is there any information which Digital cameras use a pre-flash to assist in
auto-focusing when using the built in flash.
Most or all Olympus cameras use the pre-flash system, which means that using
a slave to fire another flash would not work, because the pre-flash would
fire the slave flash unit(s). Supposedly setting the camera to Manual-Focus
eliminates the pre-flash function, trying to manual focus most digital
cameras is very difficult.
If anyone has any info regarding this please let me know.

Thanks
Helge

email: fotoATcogecoDOTca

You know what to do with the AT and the DOT

More about : slave flash

Anonymous
February 20, 2005 10:45:57 PM

Archived from groups: rec.photo.digital (More info?)

Helge Buddenborg wrote:
> Is there any information which Digital cameras use a pre-flash to assist in
> auto-focusing when using the built in flash.
> Most or all Olympus cameras use the pre-flash system, which means that using
> a slave to fire another flash would not work, because the pre-flash would
> fire the slave flash unit(s). Supposedly setting the camera to Manual-Focus
> eliminates the pre-flash function, trying to manual focus most digital
> cameras is very difficult.

I'm not sure if it's true of all cameras, but on my camera
putting it in Manual mode just means that you're then allowed to set
shutter speed and aperture manually. Focus is still automatic.
Manual focus is a different, and optional, setting.
In Manual mode, my A75 Canon does not use pre-flash, so it's very
well-behaved with standard slave units, particularly since it lets
me set the level of the on-camera flash (to just enough to trigger
the slave without having any significant effect on the resulting
picture).
If you want to use a camera that does use pre-flash with a slave
unit then you will probably have to buy a special digital-flash
slave module which ignores the pre-flash and triggers on the main
flash. Wein, among others, makes them.

-- Ron
February 20, 2005 11:04:00 PM

Archived from groups: rec.photo.digital (More info?)

Hi Helge,

I have the Metz 28 CS-2 DIGITAL flash, which is a slave unit that automatically
adjusts to your digital camera regardless of the camera's preflash-flash
interval. It is small, and has a built-in bracket to attach the flash to the
tripod socket of the camera. It's a nice unit, with adequate power for must
uses. In the USA, the street price is about $140.

Good luck.

Morton



Helge Buddenborg wrote:

> Is there any information which Digital cameras use a pre-flash to assist in
> auto-focusing when using the built in flash.
> Most or all Olympus cameras use the pre-flash system, which means that using
> a slave to fire another flash would not work, because the pre-flash would
> fire the slave flash unit(s). Supposedly setting the camera to Manual-Focus
> eliminates the pre-flash function, trying to manual focus most digital
> cameras is very difficult.
> If anyone has any info regarding this please let me know.
>
> Thanks
> Helge
>
> email: fotoATcogecoDOTca
>
> You know what to do with the AT and the DOT
Related resources
Anonymous
February 21, 2005 3:28:52 AM

Archived from groups: rec.photo.digital (More info?)

Helge Buddenborg wrote:
> Is there any information which Digital cameras use a pre-flash to assist in
> auto-focusing when using the built in flash.
> Most or all Olympus cameras use the pre-flash system, which means that using
> a slave to fire another flash would not work, because the pre-flash would
> fire the slave flash unit(s). Supposedly setting the camera to Manual-Focus
> eliminates the pre-flash function, trying to manual focus most digital
> cameras is very difficult.
> If anyone has any info regarding this please let me know.
>
> Thanks
> Helge

Hi Helge...

I suspect you'll find that they're using the pre-flash to
set exposure rather than focus...

Take care.

Ken
Anonymous
February 21, 2005 3:32:02 AM

Archived from groups: rec.photo.digital (More info?)

On Sun, 20 Feb 2005 19:25:12 -0500, "Helge Buddenborg"
<foto@cogeco.ca> wrote:

>Is there any information which Digital cameras use a pre-flash to assist in
>auto-focusing when using the built in flash.
>Most or all Olympus cameras use the pre-flash system, which means that using
>a slave to fire another flash would not work, because the pre-flash would
>fire the slave flash unit(s).

Not all slaves. Some allow for pre-flash, it has been discussed here
before.

>Supposedly setting the camera to Manual-Focus
>eliminates the pre-flash function, trying to manual focus most digital
>cameras is very difficult.
>If anyone has any info regarding this please let me know.
>
>Thanks
>Helge
>
>email: fotoATcogecoDOTca
>
>You know what to do with the AT and the DOT
>
>
>
>
Anonymous
February 21, 2005 9:46:07 AM

Archived from groups: rec.photo.digital (More info?)

On Mon, 21 Feb 2005 00:25:12 +0000, Helge Buddenborg wrote:

> Is there any information which Digital cameras use a pre-flash to assist
> in auto-focusing when using the built in flash.

The pre-flash is to adjust the exposure not the focus in mosr cameras.

> Most or all Olympus
> cameras use the pre-flash system, which means that using a slave to fire
> another flash would not work, because the pre-flash would fire the slave
> flash unit(s). Supposedly setting the camera to Manual-Focus eliminates
> the pre-flash function,

No, it does not. If you set the camera for manual exposure, then the
pre-flash is eliminated.

> trying to manual focus most digital cameras is very difficult.

One possible way (though unnecessary for flash purpose) is to do
autofocusing and then switch to manual focus but not touch the focusing
ring. Focusing distance will remain the same.

> If anyone has any info regarding this please let me know.

--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com
Anonymous
February 21, 2005 9:46:08 AM

Archived from groups: rec.photo.digital (More info?)

On Mon, 21 Feb 2005 06:46:07 GMT, Gautam Majumdar <gmajumdar@XSPAMfreeuk.com>
wrote:
>On Mon, 21 Feb 2005 00:25:12 +0000, Helge Buddenborg wrote:
>
>> Is there any information which Digital cameras use a pre-flash to assist
>> in auto-focusing when using the built in flash.
>
>The pre-flash is to adjust the exposure not the focus in mosr cameras.

Aren't there a couple reason for pre-flash? A friend's Koni-Minolta flashes at
least 3 times when left to its own devices in auto mode. My Panasonic
pre-flashes in every mode when the internal flash is used. Even with red-eye
reducer turned off both our cameras pre-flash. My Panasonic doesn't pre-flash
using the SunPak 383 on it because the 383 isn't "dedicated" to the Panasonic
but my friend's KM (Z1 I think) even pre-flashes its dedicated external show
mounted flash.

>No, it does not. If you set the camera for manual exposure, then the
>pre-flash is eliminated.

That's what I thought, but my Panasonic proved me wrong.
February 21, 2005 12:17:10 PM

Archived from groups: rec.photo.digital (More info?)

In article <602j111420j6ljveongrt06u95mt8j8b1t@4ax.com>, k7kkg@yahoo.com
says...
> On Mon, 21 Feb 2005 06:46:07 GMT, Gautam Majumdar <gmajumdar@XSPAMfreeuk.com>
> wrote:
> >On Mon, 21 Feb 2005 00:25:12 +0000, Helge Buddenborg wrote:
> >
> >> Is there any information which Digital cameras use a pre-flash to assist
> >> in auto-focusing when using the built in flash.
> >
> >The pre-flash is to adjust the exposure not the focus in mosr cameras.
>
> Aren't there a couple reason for pre-flash? A friend's Koni-Minolta flashes at
> least 3 times when left to its own devices in auto mode. My Panasonic
> pre-flashes in every mode when the internal flash is used. Even with red-eye
> reducer turned off both our cameras pre-flash. My Panasonic doesn't pre-flash
> using the SunPak 383 on it because the 383 isn't "dedicated" to the Panasonic
> but my friend's KM (Z1 I think) even pre-flashes its dedicated external show
> mounted flash.
>
> >No, it does not. If you set the camera for manual exposure, then the
> >pre-flash is eliminated.
>
> That's what I thought, but my Panasonic proved me wrong.
>
>
>

Your Panasonic is probably using the flash for low light focus assist.. You
would need to do BOTH manual Focus (difficult) and manual exposure.

I dont have one but I think thats what is happening. I shot an event last
week and several people in the crowd were using Panasonic cameras and they
all pre-flashed several (seems like 4 or 5) times before taking the picture.
The only time they didn't is when they were "stealing" shots over my shoulder
at my backdrop.. My modeling lights gave them enough light to focus, so they
only got 1 preflash per shot.


(This, by the way, is something that annoys hell out of me.. I seldom say
anything unless the shooter gets in my way, but don't you think its a little
ignorant to run up while a photographer is setting up a shot with HIS lights,
HIS bacground, and HIS time and shoot away???)


--
Larry Lynch
Mystic, Ct.
Anonymous
February 21, 2005 9:01:08 PM

Archived from groups: rec.photo.digital (More info?)

The Vivitar DF200 is a low-cost slave flash designed for digital cameras
that fire one or more extra flashes before the main flash. Besides a simple
switch setting when you know the extra flashes, it has a training mode that
learns your camera's flash characteristics.

Bye.

"Helge Buddenborg" <foto@cogeco.ca> wrote in message
news:qT9Sd.6264$RM2.5210@read1.cgocable.net...
> Is there any information which Digital cameras use a pre-flash to assist
> in
> auto-focusing when using the built in flash.
> Most or all Olympus cameras use the pre-flash system, which means that
> using
> a slave to fire another flash would not work, because the pre-flash would
> fire the slave flash unit(s). Supposedly setting the camera to
> Manual-Focus
> eliminates the pre-flash function, trying to manual focus most digital
> cameras is very difficult.
> If anyone has any info regarding this please let me know.
>
> Thanks
> Helge
>
> email: fotoATcogecoDOTca
>
> You know what to do with the AT and the DOT
>
>
>
>
Anonymous
February 21, 2005 11:07:30 PM

Archived from groups: rec.photo.digital (More info?)

On Mon, 21 Feb 2005 07:10:42 +0000, Bill Rude wrote:

> On Mon, 21 Feb 2005 06:46:07 GMT, Gautam Majumdar
> <gmajumdar@XSPAMfreeuk.com> wrote:
>>On Mon, 21 Feb 2005 00:25:12 +0000, Helge Buddenborg wrote:
>>
>>> Is there any information which Digital cameras use a pre-flash to
>>> assist in auto-focusing when using the built in flash.
>>
>>The pre-flash is to adjust the exposure not the focus in mosr cameras.
>
> Aren't there a couple reason for pre-flash? A friend's Koni-Minolta
> flashes at least 3 times when left to its own devices in auto mode. My
> Panasonic pre-flashes in every mode when the internal flash is used.
> Even with red-eye reducer turned off both our cameras pre-flash. My
> Panasonic doesn't pre-flash using the SunPak 383 on it because the 383
> isn't "dedicated" to the Panasonic but my friend's KM (Z1 I think) even
> pre-flashes its dedicated external show mounted flash.
>
>>No, it does not. If you set the camera for manual exposure, then the
>>pre-flash is eliminated.
>
> That's what I thought, but my Panasonic proved me wrong.

Yes, you are absolutely right. When I checked an old Panasonic compact
film camera I found that it uses the built-in flash for autofocus, even in
daylight. Obviously, different makes use the in-built flash for different
purposes.


--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com
Anonymous
February 24, 2005 7:30:55 PM

Archived from groups: rec.photo.digital (More info?)

>Is there any information which Digital cameras use a pre-flash to assist in
>auto-focusing when using the built in flash.

I don't think the pre-flash is for focus. The pre-flash is for
exposure. This is important because it means that many cameras (all
cameras?) that use a pre-flash in automatic mode do NOT use a
pre-flash in manual mode. I have an old-ish Canon S30, which uses a
pre-flash in all but manual exposure mode.

-Joel

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Anonymous
February 24, 2005 7:56:09 PM

Archived from groups: rec.photo.digital (More info?)

On Thu, 24 Feb 2005 16:30:55 GMT, joel@exc.com (Dr. Joel M. Hoffman)
wrote:

>>Is there any information which Digital cameras use a pre-flash to assist in
>>auto-focusing when using the built in flash.
>
>I don't think the pre-flash is for focus.

Correct, AF takes a lot longer than a pre-flash lasts. An AF assist
light is sometimes used in dark situations to help AF, but this is not
a flash.

>The pre-flash is for exposure.

Yep.

--
Owamanga!
Anonymous
February 24, 2005 10:08:29 PM

Archived from groups: rec.photo.digital (More info?)

"Owamanga" <nomail@hotmail.com> wrote in message
news:a02s119ndr9km5qfi2hfg596tevboa52ra@4ax.com...
> On Thu, 24 Feb 2005 16:30:55 GMT, joel@exc.com (Dr. Joel M. Hoffman)
> wrote:
>
>>>Is there any information which Digital cameras use a pre-flash to assist
>>>in
>>>auto-focusing when using the built in flash.
>>
>>I don't think the pre-flash is for focus.
>
> Correct, AF takes a lot longer than a pre-flash lasts. An AF assist
> light is sometimes used in dark situations to help AF, but this is not
> a flash.

It is on the *ist DS - the on-board flash strobes for a few cycles.
Very effective it is too, though it is a pain for even intelligent slave
flashes.

>>The pre-flash is for exposure.
>
> Yep.

Agreed.
Anonymous
February 26, 2005 4:22:17 PM

Archived from groups: rec.photo.digital (More info?)

Gautam Majumdar <gmajumdar@XSPAMfreeuk.com> writes:

> On Mon, 21 Feb 2005 00:25:12 +0000, Helge Buddenborg wrote:
>
> > Is there any information which Digital cameras use a pre-flash to assist
> > in auto-focusing when using the built in flash.
>
> The pre-flash is to adjust the exposure not the focus in mosr cameras.

True but some cameras (like the Canon 20D and Olympus E300 do use the flash as
an aid in focusing).

> > Most or all Olympus
> > cameras use the pre-flash system, which means that using a slave to fire
> > another flash would not work, because the pre-flash would fire the slave
> > flash unit(s). Supposedly setting the camera to Manual-Focus eliminates
> > the pre-flash function,
>
> No, it does not. If you set the camera for manual exposure, then the
> pre-flash is eliminated.

No, on most Olympus cameras this is not true. I thought this originally when I
wrote my Olympus flash FAQ many years ago, but Olympus cameras will put out the
preflash by default. A few cameras have a slave mode option that dispenses
with the preflash. Off the top of my head, the 5050 and 8080 are two that have
it, and the 5060/7070 might.

> > trying to manual focus most digital cameras is very difficult.

Most non SLR digital cameras perhaps, though some digital cameras help by
zooming into the center on the EVF to give you a better image of the focus.

> One possible way (though unnecessary for flash purpose) is to do
> autofocusing and then switch to manual focus but not touch the focusing
> ring. Focusing distance will remain the same.
>
> > If anyone has any info regarding this please let me know.

--
Michael Meissner
email: mrmnews@the-meissners.org
http://www.the-meissners.org
!