Need help choosing a relay

I am working on a project involving a Gigapan Epic 100 robotic camera mount. I want to make an activation cable for my camera, which I know will involve a relay. I have the fabrication skills to put it together but I don’t have the basic electronics knowledge to choose the proper components.

The Gigapan has: constant 5VDC out, switched 5VDC out (which should trigger the camera), and a common lead. Peak current is approximately 500ma, and from the factory is used to activate a HiTec HS-322HD to physically push the camera shutter button. I want to use the switched 5VDC to activate a relay that will close a circuit which will trigger the camera shutter electronically. I don’t have specs on the camera circuit, but it would be very low voltage.

I know that I at least need a relay, just not which one. Hoping that someone will take pity on me and share some knowledge!