Easy question about voltage?

I have an a/c adapter for a surveillance camera and it has an input of 120v ac and an output of 12v dc. I don't know what the current (amperage) is or how to find it. I also have a battery holder that holds 8 AA batteries. I've replaced the a/c adapter with the batteries but I don't know if the batteries will have enough current (amperage) to get the camera to work. How do I find the amperage, how much amperage does 8 AA batteries have and will it work if I exchange the batteries for the a/c adapter?