580EX and stobes simutaneously

Is it possible, as well as safe to have strobes attached to the sync port and then have a external flash, such as the 580ex attached to the camera when shooting in the studio? I wanted to add a little extra light and was wondering if it would affect the camera/flash in anyway. Thanks.

IF you have a 580 on the camera, I would use that to trigger the strobes, so you could go 'cordless'.
Set the 580 to 'M' though, otherwise the ETTL preflash will give problems.

I just wanted to observe that two different people have very recently posted topics on 'stobes'...I guess the synch speed has been exceeded between the brain and the index finger of the left hand!

From a technical standpoint there is no problem using both a hotshoe flash and something else connected to the PC socket at the same time. The camera will fire them both.

Whether it's a good idea from a practical standpoint is another story, as Rene' alluded.

I can neither confirm nor refute Lon's cautions, but just to clarify the source of my information, here is a piece of the instruction manual for the 20D. Note the shaded area at the bottom of the page.

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Curtis N wrote in post #2675309
I can neither confirm nor refute Lon's cautions, but just to clarify the source of my information, here is a piece of the instruction manual for the 20D. Note the shaded area at the bottom of the page.

Curtis,

This is a very important citation on your part.

This seems to indicate that Canon most likely has protective circuits in place, and it is not just a simple junction point as was possible, and the most prudent safety assumption (without very detailed specific knowledge of Canon's approach).

I did cover the possibility that Canon may have safeguards in place, in my post, but most reasonable readers would have never have given that declarative part proper weight and ignored the post if that was the case.

So, based on this, I consider my post disinformation (pure swill) and have removed it.

Thank you for clearing this up it is most appreciated.

Enjoy! Lon

londuck wrote in post #2675406
Curtis,

This is a very important citation on your part.

This seems to indicate that Canon most likely has protective circuits in place, and it is not just a simple junction point as was possible, and the most prudent safety assumption (without very detailed specific knowledge of Canon's approach).

I do not see where a statement "both connection points can be used at the same time" can have ANY implicition that the two are tied together -- or not! They could be isolated from each other and dual trigger circuits; or they could be tied together on a single trigger circuit.

Simple example: I can plug two flash units into one PC junction connector and run a single cable from my camera to trigger both lights. True parallel connection.

Counter example: I can plug one flash unit into my PC connector of my camera and use a radio slave (which presumably you do not know about) and trigger both lights at the same time from my camera...yet the two flash units are not connected together.

In the first example one flash could harm the other, in the second example one flash cannot harm the other. So what could I infer about the connection and the protection? Nothing! I only know that both can be triggered at the same time.