Why does my camera not see the slave flash?
 

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 ...
--

Henry Law Manchester, England

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 ...

Hi Henry...

I have (had) the same problem; gave up... :(

Don't know your camera, but most fire a pre-flash;
so close in time to the main flash that our eyes
can't distinguish between the pre and main flash.

This pre-flash is triggering your slave, so that the
picture comes out much much worse than it would have
had the slave not been used at all.

Happy New Year

Ken

The 300D is fireing a preflash.
If you hold the * button, he wil fire it only once.
So when you press the shutter, he will fire one flash and the slaves will go
off at the right time.
Just hold the * button and you can take the next pictures whitout the
preflash.

That works very well, i use it with two flashes and a slavetrigger.
You can test this by taking a picture of the slaveflash so you can see if it
went off.

Good luck,

Edwin Bont, holland

The 300D is fireing a preflash.
If you hold the * button, he wil fire it only once.
So when you press the shutter, he will fire one flash and the slaves will go
off at the right time.
Just hold the * button and you can take the next pictures whitout the
preflash.

That works very well, i use it with two flashes and a slavetrigger.
You can test this by taking a picture of the slaveflash so you can see if it
went off.

Good luck,

Edwin Bont, holland

I see that you have specific information for your camera...for others, and
maybe you too, often the manual mode will not fire a pre-flash.

"Henry Law" wrote in message
...
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 ...
--

Henry Law Manchester, England

I see that you have specific information for your camera...for others, and
maybe you too, often the manual mode will not fire a pre-flash.

"Henry Law" wrote in message
...
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 ...
--

Henry Law Manchester, England

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 ...

Many digicams (Perhaps the 300D) give a preflash in addition to the main
flash.
Since you "desensitized" the slave, you may be firing on the Main flash
when the slave is farther away or off to one side.
When the slave is closer and in a more direct line with your camera, it
is probably firing on the Preflash. :-(
Put a few more thicknesses of tissue over the slave when it is up close
or in a more direct line to the camera and see what happens
Bob Williams

On Sun, 02 Jan 2005 02:31:48 -0800, Bob Williams
wrote:

Henry Law wrote:

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

Many digicams (Perhaps the 300D) give a preflash in addition to the main
flash.
Since you "desensitized" the slave, you may be firing on the Main flash
when the slave is farther away or off to one side.
When the slave is closer and in a more direct line with your camera, it
is probably firing on the Preflash. :-(

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!
--

Henry Law Manchester, England

On Sun, 02 Jan 2005 02:31:48 -0800, Bob Williams
wrote:

Henry Law wrote:

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

Many digicams (Perhaps the 300D) give a preflash in addition to the main
flash.
Since you "desensitized" the slave, you may be firing on the Main flash
when the slave is farther away or off to one side.
When the slave is closer and in a more direct line with your camera, it
is probably firing on the Preflash. :-(

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!
--

Henry Law Manchester, England

There are digital slaves that fire with the main flash.

"Henry Law" wrote in message
...
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 ...
--

Henry Law Manchester, England