I've read that some older flashes can harm newer digital cameras. Something to do with too high voltage? Someone said something about how using an old flash can "fry" your camera, which I really don't want to happen. I can get a used flash, I actually have one here but am worried that it's going to do something to my camera. Perhaps I'm wrong on that though. Is any flash okay?

I'm also having trouble finding an infrared filter to cover the flash I'll be using as a trigger. Where might one find those?

Thanks so much for all your help!! It's taken me some time to figure out what you all mean by some of the things you've said but I think I'm starting to get it now.

Nothing can be simple, can it? haha

Thanks a bunch!

To point #1: I know this but the reason I need two external flashes is only because of the pre-flash, isn't it? Which is why I was hoping there was some way to turn off the pre-flash, which, obviously, isn't the case. Which is why I said I was screwed. Because that was how I'd hoped I could do it and now I've realized that I can't.

To point #2: I was using the Sigma on the slave setting and am aware that it doesn't work with pre-flash. That's the whole reason for my post. haha.

I'll work on trying what you've mentioned above and see how it goes.

Thanks!

Sorry, I'm using the DL.

This IS what I was hoping to do. Are the 500 Sigmas and the new Pentax flashes the only ones that are compatible with the DL? If I could just put a cheap flash on the hotshoe to trigger the slaves then the problem would be solved. But I'm thinking that a flash compatible for use with this camera's hotshoe is going to run another $300 or so. Which just isn't feasible.
I'm screwed.
And I was hoping to use this setup for living things (people, animals, etc.).

Oh, and I don't know what "brolley" means! hahaha

I am wishing with all my might right now that someone is going to be able to help me with this!

Today I bought an AC slave as well as a sigma EF-500 super. I set them both up, with the AC on a light stand and the sigma shooting through an umbrella. My problem is this: They aren't synching. I suspect it's because of a pre-flash firing from the Pentax for metering purposes. If this is the reason, is there any way to turn off the pre-flash? I can't seem to find any way. If not, is there some other way I can sync these off-camera flashes? I'm so disappointed right now.

Please, someone help!