Why does my camera not see the slave flash?

Henry Law wrote in
:

Playing around with my new EOS 300D to see what my old equipment
can do; flash this evening.

I have a Vivitar 283 and an old Vivitar slave (the little
cylindrical one); fitted them up on a tripod and put some tissues
over the built-in flash so it was just bright enough to trigger
the slave.

Sometimes the shot doesn't show the flash (well not the main one),
sometimes it does. Why would that be?

Try with the camera set to manual mode.
I have a Canan G5 and this works.
The Wein PN-XLD Ultra slave works reliably with the
on-board flash or a Canon 420EX flash mounted on the
camera. It does not work with the Wireless Emitter
and the flash off the camera. However, it works in
manual mode in the above conditions.

Some of the electronics stores have kits for slaves
which can count the pre-flashes. The number of
pre-flashes can be set. I have not tried these.

Good Luck.

Henry Law wrote in
:

Playing around with my new EOS 300D to see what my old equipment
can do; flash this evening.

I have a Vivitar 283 and an old Vivitar slave (the little
cylindrical one); fitted them up on a tripod and put some tissues
over the built-in flash so it was just bright enough to trigger
the slave.

Sometimes the shot doesn't show the flash (well not the main one),
sometimes it does. Why would that be?

Try with the camera set to manual mode.
I have a Canan G5 and this works.
The Wein PN-XLD Ultra slave works reliably with the
on-board flash or a Canon 420EX flash mounted on the
camera. It does not work with the Wireless Emitter
and the flash off the camera. However, it works in
manual mode in the above conditions.

Some of the electronics stores have kits for slaves
which can count the pre-flashes. The number of
pre-flashes can be set. I have not tried these.

Good Luck.

On Sat, 01 Jan 2005 21:03:13 +0000, Henry Law wrote:

Playing around with my new EOS 300D to see what my old equipment can do;
flash this evening.

I have a Vivitar 283 and an old Vivitar slave (the little cylindrical
one); fitted them up on a tripod and put some tissues over the built-in
flash so it was just bright enough to trigger the slave.

Sometimes the shot doesn't show the flash (well not the main one),
sometimes it does. Why would that be? I took a series of shots at 1/60
f/5.6 (chosen by the camera on "P" setting) and 200ASA. If the slaved
283 is above the subject to my right, or at 90deg to the subject over to
my left the shot comes out properly exposed, i.e. I can see the effects
of the slave flash. But if the 283 is closer in to the line of shot (on
a table down slightly to my left and in front of me, out of view) then
the shot is dark, with just the effect of the built-in flash and the
room lighting. Same exposure. And yes, I checked that the slave had
fired: first I could see it out of the corner of my eye and also I could
hear it re-charging.

The only thing I can think of is a synch problem, but I can't imagine
how it would happen. Light doesn't take an overly long time to get
across my living room ...

This is from my experience with EOS300 (NOT D) but I assume that the
in-built flashes work in the same way. If you use autofocus, the flash
will fire at a lower power for focusing before it fires to take the
picture. This focusing flash would often fire the slave. I avoided that by
using manual focusing.

--

Gautam Majumdar

Please send e-mails to

On Sat, 01 Jan 2005 21:03:13 +0000, Henry Law wrote:

Playing around with my new EOS 300D to see what my old equipment can do;
flash this evening.

I have a Vivitar 283 and an old Vivitar slave (the little cylindrical
one); fitted them up on a tripod and put some tissues over the built-in
flash so it was just bright enough to trigger the slave.

Sometimes the shot doesn't show the flash (well not the main one),
sometimes it does. Why would that be? I took a series of shots at 1/60
f/5.6 (chosen by the camera on "P" setting) and 200ASA. If the slaved
283 is above the subject to my right, or at 90deg to the subject over to
my left the shot comes out properly exposed, i.e. I can see the effects
of the slave flash. But if the 283 is closer in to the line of shot (on
a table down slightly to my left and in front of me, out of view) then
the shot is dark, with just the effect of the built-in flash and the
room lighting. Same exposure. And yes, I checked that the slave had
fired: first I could see it out of the corner of my eye and also I could
hear it re-charging.

The only thing I can think of is a synch problem, but I can't imagine
how it would happen. Light doesn't take an overly long time to get
across my living room ...

This is from my experience with EOS300 (NOT D) but I assume that the
in-built flashes work in the same way. If you use autofocus, the flash
will fire at a lower power for focusing before it fires to take the
picture. This focusing flash would often fire the slave. I avoided that by
using manual focusing.

--

Gautam Majumdar

Please send e-mails to

On Sun, 2 Jan 2005 19:50:01 +0000 (UTC), Peter Gordon
wrote:

Henry Law wrote in
:

Playing around with my new EOS 300D to see what my old equipment
can do; flash this evening.

I have a Vivitar 283 and an old Vivitar slave (the little
cylindrical one); fitted them up on a tripod and put some tissues
over the built-in flash so it was just bright enough to trigger
the slave.

Sometimes the shot doesn't show the flash (well not the main one),
sometimes it does. Why would that be?

Try with the camera set to manual mode.
I have a Canan G5 and this works.

OK, with all your help I've found a foolproof method for this. Manual
mode was a good suggestion but actually doesn't work - the Canon EOS
300D still fires the pre-flash (why, we might all ask, since it's not
doing its own metering). Edwin Bont's suggestion of using the "*"
button to fire the pre-flash on its own, leaving only the main flash
is the key to this, but the problem with that is that you use two
flashes - and two lots of charge-up time - for each shot.

So now I use a modified version of Edwin's method: when I press the
"*" button to fire the pre-flash I put my hand over the built-in flash
and stop it triggering the slave, then take it away and press the
button.

I tried Bob Williams' suggestion - of tailoring the amount of
attenuation of the built-in flash (read: kitchen paper folded over it)
so that the pre-flash is too weak to fire the slave. It also works
but needs to be re-done specially for each flash setup. OK for lots
of shots the same.

Thanks all. Though I will think about getting a slave unit that
understands pre-flashes; it would be a lot more convenient. All that
pressing and holding buttons with fingers and thumbs on the one hand,
while waving the other one around, is tempting Murphy too much.
--

Henry Law Manchester, England

On Sun, 2 Jan 2005 19:50:01 +0000 (UTC), Peter Gordon
wrote:

Henry Law wrote in
:

Playing around with my new EOS 300D to see what my old equipment
can do; flash this evening.

I have a Vivitar 283 and an old Vivitar slave (the little
cylindrical one); fitted them up on a tripod and put some tissues
over the built-in flash so it was just bright enough to trigger
the slave.

Sometimes the shot doesn't show the flash (well not the main one),
sometimes it does. Why would that be?

Try with the camera set to manual mode.
I have a Canan G5 and this works.

OK, with all your help I've found a foolproof method for this. Manual
mode was a good suggestion but actually doesn't work - the Canon EOS
300D still fires the pre-flash (why, we might all ask, since it's not
doing its own metering). Edwin Bont's suggestion of using the "*"
button to fire the pre-flash on its own, leaving only the main flash
is the key to this, but the problem with that is that you use two
flashes - and two lots of charge-up time - for each shot.

So now I use a modified version of Edwin's method: when I press the
"*" button to fire the pre-flash I put my hand over the built-in flash
and stop it triggering the slave, then take it away and press the
button.

I tried Bob Williams' suggestion - of tailoring the amount of
attenuation of the built-in flash (read: kitchen paper folded over it)
so that the pre-flash is too weak to fire the slave. It also works
but needs to be re-done specially for each flash setup. OK for lots
of shots the same.

Thanks all. Though I will think about getting a slave unit that
understands pre-flashes; it would be a lot more convenient. All that
pressing and holding buttons with fingers and thumbs on the one hand,
while waving the other one around, is tempting Murphy too much.
--

Henry Law Manchester, England

[re pre-flash triggering a slave]

A good hypothesis which fits the facts observed to date. And now that
various posts have suggested it I did some research: "The built-in
pop-up flash unit uses Canon's E-TTL system to meter flash output. It
does this by firing a low power pre-flash just milliseconds before the
main flash." (From DPReview's evaluation of the 300D)

I'll make some more careful tests and see what happens. Thanks!

Most digicams only fire the pre-flash in program modes. If you use
manual mode, you should be okay.

-Joel

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[re pre-flash triggering a slave]

A good hypothesis which fits the facts observed to date. And now that
various posts have suggested it I did some research: "The built-in
pop-up flash unit uses Canon's E-TTL system to meter flash output. It
does this by firing a low power pre-flash just milliseconds before the
main flash." (From DPReview's evaluation of the 300D)

I'll make some more careful tests and see what happens. Thanks!

Most digicams only fire the pre-flash in program modes. If you use
manual mode, you should be okay.

-Joel

----------------------------------------------------------------------------
Please feed the 35mm lens/digicam databases: http://www.exc.com/photography
----------------------------------------------------------------------------

(Dr. Joel M. Hoffman) writes:

[re pre-flash triggering a slave]

A good hypothesis which fits the facts observed to date. And now that
various posts have suggested it I did some research: "The built-in
pop-up flash unit uses Canon's E-TTL system to meter flash output. It
does this by firing a low power pre-flash just milliseconds before the
main flash." (From DPReview's evaluation of the 300D)

I'll make some more careful tests and see what happens. Thanks!

Most digicams only fire the pre-flash in program modes. If you use
manual mode, you should be okay.

At least for Olympus cameras, this is not true, the pre-flash is fired in all
modes (though there are a few models you can enable slave mode in manual mode
that eliminates the preflash). I suspect most cameras that use a preflash will
do so in manual mode as the preflash is used to judge the power of the flash
and set the white balance.

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