Canon Rebel XT flashes twice *RESOLVED

[kevinthenerd]

I'm trying to capture some fast-action without external lighting. The flash on the Canon Rebel XT flashes twice, causing me to see two of the subject. Is there a way around this? Do external flash mechanisms only flash once, avoiding this problem? Is this some kind of auto-metering on the camera? It happens in both manual and automatic modes.

 

[doan]

The first flash is called pre-flash, it uses the pre-flash to set the white balance. All consumer/pocket digicams do that. I'm suprised the the Rebel XT doesn't have a way to turn it off. The pre-flash also tends to make people close their eyes. An external flash will solve the problem, give you a lot more flash range and speed up refresh times.

The forums at dpreview.com are great for questions like this.

 

[corkyg]

That can be turned off. Check your program modes in the manual. Check your drive mode setting to make sure it is set for single shot and not multiple shots. The LCD would show a single square icon or a stacked double square icon. Then try it in P mode.

 

[Czar]

it also uses that preflash to get focus when you are autofocusing

 

[corkyg]

That is correct - in any automatic mode, the autofocus pre-flash will occur when the flash unit is engaged. That can be turned off by using manual focus.

 

[kevinthenerd]

RESOLVED. I always use the camera in manual mode, but I just realized that even in "M," my white balance was set to automatic. I set the whitebalance to flash, and I recorded the flash again on the 1000 fps CMOS camera I was using to test it, and thankfully, it's only firing once now. Thanks guys.