580EX II strange rapid flash behaviour?

I received my 580ex

II a few days ago. I

have been

using\testing it in

preparation for a

wedding. Twice It

has

done a very rapid

flash, almost a

constant "on" for a

second or two and

stopped. This was

right after a

regular

shot w\normal

settings. The flash

was set on ETTL and

camera on manual.

The image was fine,

it did it when I was

turning the camera

around to look at

the image.

 

Am I causing this by

pressing some

buttons or is the by

some design of the

flash?

 

body is a EOS rebel

XTI

 

Thanks,

Rich

Sounds like you're hitting the FEC button and the modelling light is going off. Check your manual.

In landscape position or "turning the camera around to look at the image", your thumb has to rest on the patch of vacant space to the right of the viewfinder eyepiece. As Nadine said, it it the FE lock button that will cause the Speedlite to flash.

The DOF preview button will also engage the modeling flash.

I wonder also if you inadvertently put it into slow sync or strobe mode. All those buttons and menu's are confusing at first till you get used to them.

It will do that to aid focus as well.

Sounds more like the DOF button at the base of the lens as Brian said.

Make sure you didn't set the flash to "stoboscopic" output.