20D DOF preview button fires 580

[quadphoto]

I have just upgraded to a 20D and spent a few hours yesterday getting used to all the new functions, I also tried my 580 flash with it, and by accident i pressed the depth of field preview button and it fired the flash in a strobe like burst. I have been unable to find reference to function in the 20D or the 580 instruction books, has any body else experienced this before with this camera and flash combination?

Quadphoto.

[Lotto]

Was the 580 in slave mode? I think that's 'modeling light' funtion of the 580 when you press the step down button.

[quadphoto]

Just checked and the 580 is not in slave mode, thanks for your reply Lotto.

[Ian Parkin]

Page 41 of my instruction book for the 580

Ian

[quadphoto]

Thanks Ian, just had a look at page 41 didnot think to look in the Wireless Flash section.