Canon 350D using slaves

[quberoot]

Hello all, I am new to this forum as I have only had my Canon 350D for 2 weeks. :)

Is it possible to use the built in flash with this camera to fire off a couple of slave units please. I get the feeling when I tried this that the slaves fired off before the built in flash fired properly. Maybe its just me :confused:
Thanks
quby

[jamison55]

You can use the onboard flash to fire off-camera slaves, but only if the slaves take into account the ETTL pre-flash. If not, the slaves will fire with the pre-flash (which sets the exposure) and cause your picture to be extremely underexposed.

[quberoot]

Thanks, thats what I thought was happening, I have heard of a cure for the Canon 350D to stop it from doing a pre-flash first. Does anyone know of this.

Thanks.
Quby

[Rhys]

Thanks, thats what I thought was happening, I have heard of a cure for the Canon 350D to stop it from doing a pre-flash first. Does anyone know of this.

Thanks.
Quby

Put it on manual/aperture priority/shutter priority rather than program mode? Actually, manual mode would be better. You know the flash synch. You should know what aperture to use, given a flash meter or the distance from the subject and guide number of the flash.

[jamison55]

I don't know of any way to disable the ETTL preflash on the built-in flash of any Canon DSLR. To trigger my external strobes I always use a shoe mount flash. Any cheap non-ETTL shoe mount can be used in the hot shoe (just be careful of the sync voltages). Since the manual flashes don't use the ETTL pre-flash to determine exposure they won't prematurely trip the slaves. The only downfall is that you have to meter manually as well.

[Rhys]

I don't know of any way to disable the ETTL preflash on the built-in flash of any Canon DSLR. To trigger my external strobes I always use a shoe mount flash. Any cheap non-ETTL shoe mount can be used in the hot shoe (just be careful of the sync voltages). Since the manual flashes don't use the ETTL pre-flash to determine exposure they won't prematurely trip the slaves. The only downfall is that you have to meter manually as well.

Isn't there a PC socket? What;s the ETTL pre-flash for anyway? (somebody who never uses flashes with digital cameras)

[jamison55]

Isn't there a PC socket? What;s the ETTL pre-flash for anyway? (somebody who never uses flashes with digital cameras)

No PC socket on the DReb. ETTL is the Canon flash metering system. It sends out a quick pre-flash to determine the correct flash exposure then sends out the "real" flash. It is pretty darned effective on the 20D (and I assume the XT). It was a bit of a challenge on the DReb...

[Rhys]

No PC socket on the DReb. ETTL is the Canon flash metering system. It sends out a quick pre-flash to determine the correct flash exposure then sends out the "real" flash. It is pretty darned effective on the 20D (and I assume the XT). It was a bit of a challenge on the DReb...

As long as the preflash is initiated as soon as the shutter opens, I see no problem. The only problem is if it's fired before the shutter opens. In that case, perhaps a capacator could be used to delay the studio flash by a long-enough time period?

[quberoot]

Hey thanks guys,

I did find that the slave units fired off with the pre-flash and can't re-charge quick enough for the main flash. What would happen if I kept the button half pressed (After the first pre-flash) wait for the other 2 slave uinits to re-charge then press the button home. Would this be just a waste of time as the camera has already pre notified itself of the exposure it's going to take.

There must be a way around this without going to the expence of buying a another flash unit for the canon.

Thanks again.
Quby

[jamison55]

The ETTL pre-flash doesn't happen when you half depress the shutter, but a fraction of a second before the real flash (after you fully depress the shutter). If the flash is firing when you half depress the shytter, it is probably the AF Assist. You might be able to work around it using the FEL (*) button. Press the FEL button, then wait for the slaves to recharge, then press the shutter...

[quberoot]

Thanks, I will try that tonight and see what happens.

Quby

;)