How about this strobist set up?

[Frankie T Fotografia]

I got this crazy idea to attach my Speedlites to my shoe adapters to create this crazy contraption I didn't fire the flashes like this because I have to buy more AA batteries. This requires 32 of them. I'm guessing the effect would be similar to a ring flash. One very expensive and heavy ring flash  I wouldn't realistically try using this setup because it's heavy, awkward, and not that sturdy. Just did it for fun and thought I'd share 

[neuroanatomist]

Sort of the ultimate ring light.  How would you trigger them?

[Frankie T Fotografia]

Triggering them is the problem. I was thinking of using a 7D to trigger them, but I haven't looked into how to connect this 5D Mark III to a 7D so that they both fire at the same time.

[briansquibb]

Fire them though PW/Odins/why

Make good lights for shooting sport

I have used a 2 flash setup at a wedding with out problems (this was pre PW - just using IR bounce off the umbrella)

[Drizzt321]

Triggering them is the problem. I was thinking of using a 7D to trigger them, but I haven't looked into how to connect this 5D Mark III to a 7D so that they both fire at the same time.

You could always get a bunch of PC sync cables, and cut off the ends and solder them all together onto 1 PC cable to the camera.

[wickidwombat]

Triggering them is the problem. I was thinking of using a 7D to trigger them, but I haven't looked into how to connect this 5D Mark III to a 7D so that they both fire at the same time.

You could always get a bunch of PC sync cables, and cut off the ends and solder them all together onto 1 PC cable to the camera.

would this work?
would you retain ettl or just be stuck with manual assuming it worked?no need to cut them you can just get a 3.5mm multi port splitter and plug into a radio trigger

[Drizzt321]

Triggering them is the problem. I was thinking of using a 7D to trigger them, but I haven't looked into how to connect this 5D Mark III to a 7D so that they both fire at the same time.

You could always get a bunch of PC sync cables, and cut off the ends and solder them all together onto 1 PC cable to the camera.

would this work?
would you retain ettl or just be stuck with manual assuming it worked?no need to cut them you can just get a 3.5mm multi port splitter and plug into a radio trigger

PC Sync doesn't do TTL anything, no matter what, so you won't get that. If you wanted ETTL on all of them...hmm...I suppose you'd need PW/Odin or something similar. I'm not sure you can stack ETTL cables, or chain them like you would need for this. It'd be an interesting experiment though, although it'd cost you a bit of money for the ETTL cables you'd cut apart and solder. Anyone want to sponsor me? I'd need a couple of Canon speedlites, as I only have 1 right now.

[westr70]

I got this crazy idea to attach my Speedlites to my shoe adapters to create this crazy contraption I didn't fire the flashes like this because I have to buy more AA batteries. This requires 32 of them. I'm guessing the effect would be similar to a ring flash. One very expensive and heavy ring flash  I wouldn't realistically try using this setup because it's heavy, awkward, and not that sturdy. Just did it for fun and thought I'd share 

Hilarious!!!  Well done.  Now put it on amazon and sell it for $10,000.00. 

[RC]

Triggering them is the problem. I was thinking of using a 7D to trigger them, but I haven't looked into how to connect this 5D Mark III to a 7D so that they both fire at the same time.

You could always get a bunch of PC sync cables, and cut off the ends and solder them all together onto 1 PC cable to the camera.

would this work?
would you retain ettl or just be stuck with manual assuming it worked?no need to cut them you can just get a 3.5mm multi port splitter and plug into a radio trigger

PC Sync doesn't do TTL anything, no matter what, so you won't get that. If you wanted ETTL on all of them...hmm...I suppose you'd need PW/Odin or something similar. I'm not sure you can stack ETTL cables, or chain them like you would need for this. It'd be an interesting experiment though, although it'd cost you a bit of money for the ETTL cables you'd cut apart and solder. Anyone want to sponsor me? I'd need a couple of Canon speedlites, as I only have 1 right now.

Oh come on, nobody read Syl's book?     Set one as the master and bounce the signal back or better yet, place the master pointing back at the cluster connected via an extra long ETTL cable.   

The real question is how do you hold that beast steady?

[dr croubie]

Are any of the 550/580/600EXs?
I'm not sure what's attached to the camera, whether it's a real hot-shoe or just a coldshoe, but what you could do (presuming it's just a coldshoe), get a flash cable and connect to one as master, set all the others up as slaves, and hope there's enough light-bounce off the subject (or somewhere) to trigger them all...

[mws]

Maybe you can sell it to the Navy, they can blind somali pirates from a distance.

[PeterJ]

I'm not sure you can stack ETTL cables, or chain them like you would need for this. It'd be an interesting experiment though, although it'd cost you a bit of money for the ETTL cables you'd cut apart and solder. Anyone want to sponsor me? I'd need a couple of Canon speedlites, as I only have 1 right now.

Classic shot by the OP . You wouldn't be able to stack ETTL cables, they are an SPI like interface where you have a a master / slave type arrangement. When the master (the camera) sends the commands to the slaves (flashes) they would all try to respond at the same time. When you want to stack that kind of interface you normally need a seperate chip select type line to force the slaves into a high impedance which Canon flashes don't allow for from my reading.

Only way I think would be a microcontroller that sat between all the flashes and the camera and actually interpreted and tried to respond intelligently to the requests, like maybe firing a pre-flash from all flashes for metering but then only returned metering information back from the central one so the camera thought it was dealing with a single unit.

[Drizzt321]

I'm not sure you can stack ETTL cables, or chain them like you would need for this. It'd be an interesting experiment though, although it'd cost you a bit of money for the ETTL cables you'd cut apart and solder. Anyone want to sponsor me? I'd need a couple of Canon speedlites, as I only have 1 right now.

Classic shot by the OP . You wouldn't be able to stack ETTL cables, they are an SPI like interface where you have a a master / slave type arrangement. When the master (the camera) sends the commands to the slaves (flashes) they would all try to respond at the same time. When you want to stack that kind of interface you normally need a seperate chip select type line to force the slaves into a high impedance which Canon flashes don't allow for from my reading.

Only way I think would be a microcontroller that sat between all the flashes and the camera and actually interpreted and tried to respond intelligently to the requests, like maybe firing a pre-flash from all flashes for metering but then only returned metering information back from the central one so the camera thought it was dealing with a single unit.

Good to know, and kinda what I thought. Now, if those were all the new 600EX (or using another RF ETTL system), he could easily have them all working over RF. Although...I wonder if there might be problems because they're so freaking close between the master/slaves?