Red light Camera ticket

Does an officer, who called to testify in court about red light camera
violation, but was not on site at the time when the actual violation
has happened, can be legally called \"a witness\"?

Well he can but his testimony will only be relevant to the extent that he has actual knowledge and facts.

A big issue is whether the photos and issuing of citations are handled by a private vendor. The photos could be excluded as hearsay, since they would not fall under the exceptions for a public employee or government records.