I have a Sigma EF-610 DG ST flash which fits my Sony A55 and takes perfectly good pictures. I would like to be able to detach the flash from the camera and trigger it remotely (for preference) or through a cable, whilst still maintaining the TTL facility. I'm told that some remotes will respond to the built-in flash on the Sony. I have looked at various devices on the net, but they do seem rather vague as to whether they will actually maintain the TTL aspect. Does anyone have any suggestions?