You can try as testing flash yours 580EX, just insulate all contacts except central one and ground contact (contact that is placed on side of flash foot, not on bottom of flash foot). I did that, I used mine Speedlite 380EX like that with several other non Canon cameras. Because hot shoes on cameras are metal, I put insulation (very thin piece of plastic, or put electrical insulation tape) on hot shoe, so I only have central contact of hot shoe and sides of hotshoe not insulated. So, when put mine 380 EX on cameras hot shoe, all 380's contacts except central one were insulated from metal part of cameras hot shoe. So, only central contact of 380 was in touch with hot shoe central (hot) contact and ground (side) contact of 380 EX was in touch with side of metal part of hot shoe (ground contact of hot shoe). Of course, you loose all controls over flash, you only can trigger it, but as testing flash it will work. That way you also avoid preflash of Speedlite, you only have exposing flash, ant that is what you need
. Warning, if you are afraid to cause malfunction of 580EX with this method, then find another flash, if you try, you will do that at your own risk...