Would this be possible?!

i've had an idea for an app but i'm not sure whether it will be possible or not. Well, I think it's definatly possible, but it's whether it'll be fast enough!

Basically, I want to use the camera to detect a flash, and then if there is a flash, the phone's camera will flash too. Basically using the phone as a remote flash.

What do you think? Would I be able code something fast enough to register a flash on the camera and then set the phone's flash off?

 

It's the temperamental side of it that I was asking about whether it would eb possible really!

In theory, it's visible on the camera screen everytime my dslr flashes, so it should definitely be possible to code something to register the flash anomaly on the screen. I guess it would be kind of similar to how the old light guns (duckhunt games) used to work in a way.

Yeah, the main question is whether the flash would be quick enough as I'd be relying on the camera rather than a dedicated sensor.

And then the ultimate question is, would it actually be any use?!

I think as an idea it's alright, but seeing as I'd be using a