shoe-mount vs off-camera flash/speedlights
You can use shoe mount flashes off camera. The type of remote trigger you need depends on the flash you get. Most of the Sony flashes can use the Sony IR wireless system with TTL. I don't know the A33 so I can't say if the built in flash (?) will control a Sony off camera flash. If not one solution is to use Sony "20" flash as the on camera 'transmitter' to control the off camera flash. Only works with Sony flash as far as I know.
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